Changing the date on the sub form

[Allie]

My main form and sub form (datasheet) are linked by the
date field and another field. If the date is changed on
the main form, I would like the dates on the subform to
change automatically.

I've tried an If statement on the exit event of the date
on the main form with
forms!fSubForm!txtDate = forms!frmMainForm!txtDate

Problem: when the exit event of the main form date runs,
it gives the error message that it cannot find the sub
form.

Any suggestions?

Thanks