Try setting the grid's ControlSource to the result of your UDF:
ControlSource=MyDateFunction(dField)

>Hi all,
>
>I'm really stuck with the following problem in VFP 3.0b:
>
>In a grid cell's (datasource is a date field) Valid event I'm passing the value of the field (a date) to the external PRG in order to make the date entered Y2K compliant, e.g. year 02 is converted to 2002, 54 to 1954 based on my rollover year etc. This works fine and the value of the cell is programatically changed, however for some reason the year always defaults back to 19xx t. When LostFocus event is fired, it already shows 19xx value for the year. Could someone please, please help me with this, it's very urgent and important. Many thanks in advance,
>
>Srdjan