I made $12k last year but I cannot get the pell grants. WHY?

I just filed the tax return into financial aid application. The outcome is I do not get any pell grants and I can only get the loan.
I am 21years old, so I need to put in my parent's information.
However, my father is 61 years old, and he is already retired, so he got no income at all.
I need to pay for my own rent, insurance, and his rent, etc.
I do not get it why I am not qualify for the pell grants even few hundred bucks.
Is $12k is not low income for single or 2 people family?

Thanks for answering.