HELP! Why did turbotax allow me to list a chartible contribution when I selected the standard deduction???? IRS Kicked back my return.

Turbotax correctly entered standard deduction amount correctly on line 12a of 10,390  but it allowed me to enter a charitible contribution on 12b  which it shouldn't have because that is not allowed for the standard deduction right ?  Now I have the IRS asking for a schedule A.  What do I do ?????