I have just normal graphs on my TI 84, with some shading, and I went to turn the axes off and all the sudden I couldn't access my graph cause it said ERR:UNDEFINED. And believe me, turning the axes on didn't do anything. This problem has been going on all day and I found a mistake in an equation and fixed it, but I have checked and checked and CHECKED for more mistakes and I can't find any!! Now I can't access my graph, and this is part of my homework. I don't know what to do.