Colin,

Try this instead.

.KeyPress Event
IF This.Style=2 AND This.mlListLikeCombo
   IF nKeyCode=5 &&UPARROW or DNARROW DropDown Combo
      KEYBOARD "{BACKTAB}"
      NODEFAULT
   ENDIF
   IF nKeyCode=24
      KEYBOARD "{TAB}"
      NODEFAULT
   ENDIF
ENDIF

You won't need the Valid code anyore because you aren't changing the style for the combo.