How to uncheck box 91 on form 540 it doesn't allow?

[stracy6]

im being instructed to uncheck box 91 on form 540 but it doesn't allow to remove the check. using turbo tax online free edition

[VanessaC]

Is the amount on line 75 more than the amount on line 64? You might not be able to uncheck if your payments and credits are more than your tax.