Problem in document number auto generation

Question

Dear All,
       I have created a screen in this screen,i want to generate a auto generate number
      for that i have write a code but when am executing the program in VS2005,the form was loaded in SAPB1 2005,But am not getting the auto generate number in the particular coloumn.
It shows an error like pbject reference not set to an instance of an object
the code is,
    Private Sub DCNumber()
        Try
            oForm = SBO_Application.Forms.Item("FormEditor")
            Dim oRs As SAPbobsCOM.Recordset
            oRs = ocompany.GetBusinessObject(SAPbobsCOM.BoObjectTypes.BoRecordset)
            oRs.DoQuery("Select DocNum IS NULL THEN '1' ELSE DocNum+1 from @SCDC")
            Dim Auto As String = oRs.Fields.Item(0).Value
            oForm.Freeze(True)
            oForm.Items.Item("25").Specific.Value = Auto
            oForm.Freeze(False)
        Catch ex As Exception
            SBO_Application.StatusBar.SetText(ex.Message)
        End Try
    End Sub
I call this function in,
Public Sub New()
        MyBase.New()
        SetApplication()
        ' Load the Tab Order form
        LoadFromXML("SCDC.srf")
        oForm = SBO_Application.Forms.Item("FormEditor")
        oForm.Visible = True
DCNumber()
    End Sub

Answer 1

You could use Aslam's answer but then in one row and use it in a formatted search..
select ISNULL(MAX(DocNum),0) +1 from @SCDC
I think the error is in this line:
Dim oRs As SAPbobsCOM.Recordset
oRs = ocompany.GetBusinessObject(SAPbobsCOM.BoObjectTypes.BoRecordset)
Should be:
Dim oRs As SAPbobsCOM.Recordset
oRs = (SAPbobsCOM.Recordset) ocompany.GetBusinessObject(SAPbobsCOM.BoObjectTypes.BoRecordset)
Or in:
Dim Auto As String = oRs.Fields.Item(0).Value
Dim Auto As String = oRs.Fields.Item(0).Value.ToString()
But you can set a breakpoint and debug your code, then it's possible to see where is trown the error..
HTH
Regards Teun
Edited by: Teun Aben on Apr 15, 2009 10:42 PM