Subform and validation

[Majic]

Hello everyone,
I have a form that is linked to two subforms using Tabs.
One tab (subform) has Item, quantity, scanned item, and scanned qty
that I need to make sure that they scan all items provided "Item,
Quantity" before going to next record.
Second tab (subform) has Item, Quantity and check box, I do not want
them to go to next record before the check off all checkboxes.

Any ideas, need your help

Thank you