你是刷新了报表再加载还是加载之后再刷新，
我刚刚也遇到这样问题，我刷新了一下就有数据了
        Dim rpt As New ReportDocument
        rpt.Load("..\..\CrystalReport2.rpt")
        rpt.SetDataSource(ds)
        Form5.CrystalReportViewer1.ReportSource = rpt
        'Form5.CrystalReportViewer1.RefreshReport()

刷新了还是不行

有检查过你查出来的数据集有问题吗？
比如说你数据集的字段和报表的字段不统一，这样就传不过去

昨天我在论坛有一位大哥有这样的一段文章。忘记是谁了。。请原著见谅。希望这对你有帮助



向水晶报表传递参数时，要注意的是：必须向服务器的名称、数据库名、登录名、密码传递给报表文件，如果有子报表的话，这些参数也要传递。 
下面是我的代码，各位可能要适当修改。 
本文有参考网上的一篇文章，但是哪位的我就记不得了，请原作者不要见怪。 

  Try 
                        Me.Cursor   =   Cursors.WaitCursor 

                        Dim   Num,   strRPTFile,   str()   As   String 
                        Dim   srv,   db,   user,   pwd   As   String 
                        Dim   sql   As   String 
                        Dim   dsSub   As   New   DataSet 

                        Dim   sqlConn   As   New   SqlConnection 


                        If   Me.dgrd1.DataSource   Is   Nothing   Then 
                                Exit   Function 
                        End   If 

                        If   Me.dgrd1.SelectedCells.Count   <=   0   Then 
                                Exit   Function 

                        End   If 

                        If   Me.dgrd1.CurrentCell   Is   Nothing   Then 
                                Exit   Function 
                        End   If 

                        Num   =   Me.dgrd1.Rows(Me.dgrd1.CurrentRow.Index).Cells("Num").Value 
                        If   Num   Is   Nothing   Then 
                                Exit   Function 
                        Else 

                                str   =   ConfigurationManager.AppSettings("SqlServer").Split(";") 


                                strRPTFile   =   GetReportPath("PUR",   "PUR_PO.rpt") 

                                For   I   As   Integer   =   0   To   str.Length   -   1 
                                        If   str(I).IndexOf("=")   >   0   Then 
                                                If   str(I).Split("=")(0).ToUpper   =   "Server".ToUpper   Then 
                                                        srv   =   str(I).Split("=")(1) 
                                                End   If 

                                                If   str(I).Split("=")(0).ToUpper   =   "DataBase".ToUpper   Then 
                                                        db   =   str(I).Split("=")(1) 
                                                End   If 

                                                If   str(I).Split("=")(0).ToUpper   =   "Uid".ToUpper   Then 
                                                        user   =   str(I).Split("=")(1) 
                                                End   If 

                                                If   str(I).Split("=")(0).ToUpper   =   "Pwd".ToUpper   Or   str(I).Split("=")(0).ToUpper   =   "Password".ToUpper   Then 
                                                        pwd   =   str(I).Split("=")(1) 
                                                End   If 

                                        End   If 
                                Next 

                                Dim   CMD   As   System.Data.SqlClient.SqlCommand 
                                Dim   sqlAD   As   New   SqlDataAdapter 
                                Dim   ds   As   New   DataSet 


                                Dim   myReportDoc   As   New   CrystalDecisions.CrystalReports.Engine.ReportDocument 
                                Dim   myParameterValues   As   New   CrystalDecisions.Shared.ParameterValues 
                                Dim   myDiscreteValue   As   New   CrystalDecisions.Shared.ParameterDiscreteValue 


                                strRPTFile   =   GetReportPath("PUR",   "PUR_PO.rpt") 

                                sqlConn.ConnectionString   =   ConfigurationManager.AppSettings("SqlServer") 
                                If   sqlConn.State   =   ConnectionState.Closed   Then 
                                        sqlConn.Open() 
                                End   If 


                                CMD   =   New   SqlClient.SqlCommand("Select_PO",   sqlConn) 
                                CMD.CommandType   =   CommandType.StoredProcedure 
                                CMD.CommandTimeout   =   60 

                                CMD.Parameters.Add(New   SqlClient.SqlParameter("@Num",   SqlDbType.NVarChar,   4000)) 
                                CMD.Parameters("@Num").Value   =   Num 


                                CMD.ExecuteNonQuery() 
                                CMD.Dispose() 

                                sqlAD.SelectCommand   =   CMD 
                                sqlAD.Fill(ds,   "Rptds") 


                                "向子報表傳遞參數 
                                sql   =   "exec   dbo.GetCommpanyInfo" 
                                dsSub   =   ReturnDataset(sql) 


                                Dim   logonInfo   As   New   TableLogOnInfo 
                                Dim   table   As   Table 
                                myReportDoc.Load(strRPTFile) 


                                "设置登录信息 
                                For   Each   table   In   myReportDoc.Database.Tables 
                                        logonInfo   =   table.LogOnInfo 
                                        With   logonInfo.ConnectionInfo 
                                                .ServerName   =   srv 
                                                .DatabaseName   =   db 
                                                .UserID   =   user 
                                                .Password   =   pwd 
                                        End   With 
                                        table.ApplyLogOnInfo(logonInfo) 

                                Next 


                                "向子報表傳遞登錄參數 
                                For   I   As   Integer   =   0   To   myReportDoc.Subreports.Count   -   1 

                                        For   Each   table   In   myReportDoc.Subreports(I).Database.Tables 
                                                With   logonInfo.ConnectionInfo 
                                                        .ServerName   =   srv 
                                                        .DatabaseName   =   db 
                                                        .UserID   =   user 
                                                        .Password   =   pwd 
                                                End   With 
                                                table.ApplyLogOnInfo(logonInfo) 
                                        Next 

                                        If   myReportDoc.Subreports(I).Name   =   "CommpanyInfo"   Then 
                                                myReportDoc.Subreports(I).SetDataSource(dsSub.Tables(0)) 

                                        End   If 

                                Next 

                                myReportDoc.SetDataSource(ds.Tables(0)) 


                                My.Forms.Frm_Report.CrystalReportViewer1.ReportSource   =   myReportDoc 
                                My.Forms.Frm_Report.CrystalReportViewer1.Zoom(1) 
                                My.Forms.Frm_Report.CrystalReportViewer1.DisplayGroupTree   =   False 

                                Frm_Report.ShowDialog() 


                        End   If 


                Catch   ex   As   Exception 
                        Me.Cursor   =   Cursors.Default 
                        MsgBox(ex.Message,   MsgBoxStyle.Exclamation,   "信息提示") 
                Finally 
                        Me.Cursor   =   Cursors.Default 
                End   Try 

把报表文件删掉。重新建一个。