I keep getting Error 11 (Function argument value, type, or count is invalid) when my method tries to refresh a grid- Thisform.Gridname.Refresh() . There is no code (including in parents) in Gridname.Refresh . The project, inlcuding tables and classes, is in Visual Source Safe.
Basically, if a user enters values in the Lastname textbox and Firstname textbox (both outside of the grid), I want the grid to show only records where the names match the inputted values. In other words, if you entered 'J' in the Firstname textbox and 'S' in the Lastname textbox, you would see the records of Josh Schwartz, John Smith, Jane Summers, et al.
My code in the textboxes' InteractiveChange methods is:
****************************************
DODEFAULT()

SELECT People
SET ORDER TO Name
SET FILTER TO

DO CASE
CASE !EMPTY(ThisForm.txtFName.Value).and.!EMPTY(ThisForm.txtLName.Value)
SET FILTER TO UPPER(People.FName) = ALLTRIM(UPPER(ThisForm.txtFName.Value));
.AND.UPPER(People.LName) = ALLTRIM(UPPER(ThisForm.txtLName.Value))
CASE... &&(other cases which do SEEKs and don't cause Error 11)
ENDCASE

ThisForm.GridName.Refresh()
****************************************
Any ideas on why I'm getting Error 11 or what I can try to prevent it?

Jerry