To get into the college of winterhold you must pass a test.So when the lady asks me to cast mage light for the test, I do and nothing happens, what's wrong?

Are you selecting the right spell and aiming it at the sign on the ground?

You need to select the correct spell, or if you dont have it buy it from her for 30coins. Then you aim the spell at the gatekeeper and she lets you progress.

At least thats what i had.

Haha nope I was shooting it everywhere but the sign, thanks.