Hide dependents

Hello eveyone, for the last couple hours I've been trying to hide the dependents with no success...

I'm using this with a custom content type with custom fields

Dependee = Select List widget with two options, one activates dependents
Dependent = A: Select List / B: Integer

Anyone can help or guide me on how to accomplish? I'm really confused with all the options, and I've tried everything I think, read the documentation, google, etc...

I'm on D7.12

Thks...