Spousal Amount Problem

The introduction asks if you are eligible for the spousal amount. I initially chose Yes because below that it says TT will calculate the amount you are eligible to claim, if any, based on income and deductions. So I checked the box indicating I am not sure if I am eligible. My return is prepared with my spouse together. I am married and answered no to the questions on living apart, bankruptcy, disabled, and dependency. My spouse's net income is zero. Upon review, the spousal amount is being claimed by TT. When I change the answer to No (not eligible), it doesn't claim the spousal amount. It appears the software is not actually behaving as described/expected when you check the box about being not sure if you are eligible. 

Am I eligible for the spousal amount? If not, why is TT calculating as if I am?