I'm a FT graduate student and have a 1098-T. Turbo Tax is telling me I don't qualify for the Lifetime Learning credit but I don't know why. Any ideas?

The Lifetime Learning Credit is non-refundable.   It can only be used to reduce your tax liability.   If you have no tax liability the credit does nothing for you.

Q. Does need to be above a certain amount to get this?

A. Yes. Your taxable income must be above 0, so that you have a tax liability to offset.  Unlike the more generous American Opportunity Credit (usually not available to grad students), the  Lifetime Learning credit is "non refundable".