Discovery Credit Card Why Was I Rejected For A Student Credit Card That I Got An Offer For?

Why was I rejected for a student credit card that I got an offer for? - discovery credit card

I have an offer for a credit card for students discovered a short month before. I have to ask, and said: "insufficient credit history. Why did you send me an offer if they will reject me? Is this normal?
I'm 18 and I started college a few months ago. I have 2 student loans out, this could be why?