calling report in Visual Basic

Kindly help !!!
I am new to Visual Basic and eagerly waiting for your kind help.

I have developed a report with parameters. While running the report from form following are the error messages appear.
1. While running the report some time in debug mode report is displayed, but in normal mode it does not return any rows.
2. If I run the report for the second time then following message appears.
Run-time error '-2147217900(80040e14)';
[Microsoft][ODBC driver for Oracle]Syntax error or access violation
3. If I come out of the form and again try to run the report by invoking once again then error message is same.
4. Some times Error show maximum process limits exceeds.
I am sending the code for calling the report


Private Sub cb_print_Click()
gRegNo = Val(regNoTextBox.Text)

If DataEnvironment1.Connection1.State = 0 Then
DataEnvironment1.Connection1.ConnectionString = conn
DataEnvironment1.Connection1.Open
End If
DataEnvironment1.hst_detail_Grouping gRegNo
'SHOW THE REPORT
bill_print_detail.Show
DataEnvironment1.Connection1.Close

End Sub