I'm trying to find a model for months vs. inches of precipitation. I've entered those #s in lists 1 and 2 on my ti-84 plus. Then I followed directions, which said to select SinReg and then type L1, L2 and hit enter. I did, but I got ERR: SINGULAR MAT. Please help? Idk what's wrong, I have it in radian mode.

Any suggestions are appreciated :]