make the subform required in the master form

[CSCS]

Hi,

I have 2 forms, a master and a subform.
In the subform form there are some required fields. In the table behind the subform I choose the property of these fields to be required.
but in the master form, when I start enter the information I can go to the next record without even touching the subform.

How Can I make the subform required in the master form?

Regards,
CS.