I actually figured it out, from another support question. I'll quote it here:
"What's happening is that your income was low enough that you were assigned the Working Income Tax Benefit. Since students are excluded from this benefit, your tuition slip entry removed the benefit as it should."
You should be able to apply for the Canada Training benefit though, I was able to get $500 back from that as a student!
Not sure why your tuition is reading as 0.00 though, that seems weird!
