Charitable Cash Contributions line 12b glitch?

I ran the review of my taxes and TurboTax found an error with what appears to be the $300 that it wants to enter on line 12b as the charitable contribution when taking the Standard Deduction. It says that since we are filing MFJ, $600 should be entered. It won't accept that either. I have gone to forms view and scrolled through Step by Step. Have I missed something or do I need to wait for a software update?