Every time I try to graph on TI 84 it says ERR: INVALID DIM 1:QUIT I have enterered something simple y= x+2 and window is set for -10<x<10 and -10<y<10 the curser in y= screen is highlighted so the graph is on.

Go to http://education.ti.com/downloads/guidebooks/graphing/84p/TI84Plus_guidebook_EN.pdf to download the manual. On page 401, you will find the following:
INVALID DIM • The ERR:INVALID DIM error message may occur if you are trying to graph a function that does not involve the stat plot features. The error can be corrected by turning off the stat plots. To turn the stat plots off, press y , and then select 4:PlotsOff. • You specified a list dimension as something other than an integer between 1 and 999. • You specified a matrix dimension as something other than an integer between 1 and 99. • You attempted to invert a matrix that is not square.