请教一个VB.NET的问题

我创建了一个类,分别用来执行SELECT在WEB页面中点击按钮代码如下:却提示出错,SQL事件控查已执行过,请教一下代码错在那里?

Protected Sub Button4_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button4.Click
Dim mycon As conn
Dim dt As New Data.DataTable
Dim Rs As Data.DataSet
mycon = New conn
Rs = mycon.rsdb
Rs = mycon.QuerySql("Select * from t_UserPrv where FUser=" + "'" & TextBox1.Text & "'", "t_userPrv")
MsgBox(Rs.Tables("t_userprv").Rows(1)(0).ToString()) '运行到这出错
End Sub









'------------- 执行SQL类--------------------------------------------------------------------
Public Class conn
'Public rsdb As Data.DataSet
Public Function QuerySql(ByVal strSql As String, ByVal TableName As String) As Data.DataSet
Dim myDs As New Data.DataSet
Dim sqlConn As SqlConnection = New SqlConnection(ConfigurationManager.AppSettings("Conntction"))
Dim Myds As New Data.DataSet
Dim myCmd As SqlCommand = New SqlCommand(strSql, sqlConn)
Dim myDa As New SqlDataAdapter(strSql, sqlConn)


Try
myDa.Fill(Myds, TableName)
'rsdb = Myds
Catch er As Exception

Finally
sqlConn.Close()
End Try
Return Myds
End Function
End class