Crystal Report Calls in VB gives error

I am calling a report designed in Crystal Report in a VB Project.
I want to replace the current selection formula by another simple formula
(the same field is being in use)
But it gives the following error
example source

Private Sub Command1_Click()
Dim strSQL As String
strSQL = "{TableName.SerialNo} > " & Val(Text1.Text)
CrystalReport1.ReplaceSelectionFormula strSQL
CrystalReport1.Action = 1
End Sub


Run Time error '20536'
Unable to connect:incorrect log on parameters


HOW TO GO AHEAD?

the first thing CR tries to do is log on to the database using the logon parameters you specified.
Obivously something is wrong with those parameters. Make sure you login parameters (username, passwort, database...) are set correctly.