datagrid bug

Dear friend
I am facing a small problem when I am using datagrid cell value assignment. I want to assign the value of column 8 to column 9 of current row when I press F5

I already added following code

if keycode=116
datagrid1.column(9).value=datagrid1.columns(8).value
endif

where column 9 and column 8 contains numeric values

but it is not reflecting in the datagrid when i run the code normally.I get this value when I use breakpoint. even when I use msgbox to display the column 9 value it is displaying properly. Plese try to give me the solution for this small bug

thanks
urs
ravi