I'm a graduate student attending a university and don't qualify for the lifetime learning credit. I earned $7k last year, was it too much?

No, your income of 7,000 would not make you ineligible. 

I would guess that you do not have a tax liability for the credit to be used against.

Look at your 1040 line 16, if that is zero, the credit is useless, so the program would say you don't qualify. 

HERE is how to look at your 1040 using Online

Desktop users simply switch to FORMS 

If you only had $7K income, and are a FT student, under 24, you may still qualify as your parent's dependent.  They would qualify for the LLC.

Grad students are generally not eligible for the more generous, and partially refundable, American Opportunity Credit (AOC), except in the year they receive their BS/BA.  There is also a limit, of 4, to the number of times the AOC can be claimed.