The subform CONTROL may have a limited number of events.
The FORM that is being used as the form object of the subform control has all
the form events.
Try opening the form that is being used as a subform, then you should be able to
get to all the form events.
If you are having problems getting to the form, post back AND tell us your
version of Access. There are some differences in getting to the (subform) form
if you are not closing the main form and then opening the (subform) form from
the list of forms.