I enter the posted Control number and it won't accept it, how do I proceed?

Assuming you're referring to the control number (box D) on your W-2, you don't need to enter it (unless you may be trying to import it).

If you get errors when attempting to import your W-2 with an empty box D, select Type it in myself and manually enter your W-2.

TurboTax FAQ: I have no box D or Control Number on my W-2