WEB 与ReportingServis 连接

[anmyyan]

我是采用如下方法连接ReportingServis的
Dim rs As New ReportingService
rs.Credentials = System.Net.CredentialCache.DefaultCredentials '基本认证
Dim result As Byte() = Nothing

Dim reportPath As String = "http://yc3-a3/Reports/Pages/Report.aspx?ItemPath=%2fSample+Reports%2fEmployee+Sales+Summary"
Dim format As String = "MHTML"
Dim historyID As String = Nothing
Dim devInfo As String = "<DeviceInfo> <Toolbar>False</Toolbar> </DeviceInfo>"
' 报表参数
Dim parameters(2) As ParameterValue
parameters(0) = New ParameterValue
parameters(0).Name = "EmpID"
parameters(0).Value = "38"
parameters(1) = New ParameterValue
parameters(1).Name = "ReportMonth"
parameters(1).Value = "6" ' June
parameters(2) = New ParameterValue
parameters(2).Name = "ReportYear"
parameters(2).Value = "2004"
Dim credentials As DataSourceCredentials() = Nothing
Dim showHideToggle As String = Nothing
Dim encoding As String
Dim mimeType As String
Dim warnings As Warning() = Nothing
Dim reportHistoryParameters As ParameterValue() = Nothing
Dim streamIDs As String() = Nothing
Dim sh As New SessionHeader
rs.SessionHeaderValue = sh
Try
result = rs.Render(reportPath, format, historyID, devInfo, parameters, credentials, showHideToggle, encoding, mimeType, reportHistoryParameters, warnings, streamIDs)
sh.SessionId = rs.SessionHeaderValue.SessionId
Catch ex As SoapException
Console.WriteLine(ex.Detail.OuterXml)
End Try
' 保存为 MHTML 文件，也可以直接 Response 给客户端
Try
Dim stream As FileStream = File.Create("report.mhtml", result.Length)
stream.Write(result, 0, result.Length)
stream.Close()
Catch ex As Exception
Console.WriteLine(ex.Message)
End Try


但在两个Try中都会抛出异常

提示是To render a report, enter the ServerUrl and ReportPath.
到底是怎么回事,请大家指点