SQL Server Insert Update Stored Procedure - Does Not Work The Same Way From Code Behind

All:

 I have created a stored procedure on SQL server that does an Insert else Update to a table. The SP starts be doing "IF NOT EXISTS" check at the top to determine if it should be an insert or an update.

When i run the stored procedure directly on SQL server (Query Analyzer) it works fine. It updates when I pass in an existing ID#, and does an insert when I pass in a NULL to the ID#.

When i run the exact same logic from my aspx.vb code it keeps inserting the data everytime! I have debugged the code several times and all the parameters are getting passed in as they should be? Can anyone help, or have any ideas what could be happening?

Here is the basic shell of my SP:

CREATE PROCEDURE [dbo].[spHeader_InsertUpdate]

@FID  int = null OUTPUT,
@FLD1 varchar(50),
@FLD2 smalldatetime,
@FLD3 smalldatetime,
@FLD4 smalldatetime

AS

Declare @rtncode int

IF NOT EXISTS(select * from HeaderTable where FormID=@FID)

 Begin
  begin transaction

   --Insert record
   Insert into HeaderTable (FLD1, FLD2, FLD3, FLD4)
   Values (@FLD1, @FLD2, @FLD3,@FLD4)
   SET @FID = SCOPE_IDENTITY();
   
   --Check for error
   if @@error <> 0
    begin
     rollback transaction
     select @rtncode = 0
     return @rtncode
    end
   else
    begin
     commit transaction
     select @rtncode = 1
     return @rtncode
    end
   
   end
ELSE

 Begin
  begin transaction

   --Update record
   Update HeaderTable SET FLD2=@FLD2, FLD3=@FLD3, FLD4=@FLD4
   where FormID=@FID;

   --Check for error
   if @@error <> 0
    begin
     rollback transaction
     select @rtncode = 0
     return @rtncode
    end
   else
    begin
     commit transaction
     select @rtncode = 2
     return @rtncode
   end

End
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

 

 Thanks,

Blue.