[AccessD] A2K: Editing data in an MSFlexGrid...help!

I've got this form in an A2K app that displays data in an MS FlexGrid
control.

I'm trying to use the "tried and true" method of allowing a user to
edit data in the grid by positioning a text box over whatever cell
the user clicks.  But it's just not working.  
 
Here's the code I'm using in the grdMain_SelChange event:

[code]
With grdMain
    If .CellWidth < 0 Then Exit Sub
    txtEdit.Move .Left + .CellLeft, .Top + .CellTop, .CellWidth,
.CellHeight

End With

txtEdit.Visible = True
txtEdit.SetFocus[/code]

I have my textbox's BackColor set to bright yellow so I can see it if
it appears over the grid, but so far it just disappears when I click
the grid.  I don't knwo where it's going.  Perhaps it is beneath the
grid, in which case I don't know how to bring it to the front.  but
if it's not behind the grid, where is it?  Where am I going wrong?

-Christopher-