Check datasheet subform for value

[Sid via AccessMonster.com]

I have a main form that when the user clicks "no" on the drop-down, I need
the code to check the subform which is in datasheet view, for the value of
"open". the datasheet can have a lot of "open", but i just need to check if
any is open. If any value is open then i would give a pop up message that
there are open values in the subform.

I'm not sure how to do this with a datasheet subform. this is what I have on
the after update of the drop down:

If subform.status = 'open' then
msgbox "there are still open items. "
end if

Thanks,
Sid