Wont graph Y=

I downloaded this app in an attempt to avoid buying/borrowing a real ti-83 for algebra 2. Im currently running ios 7.0.4 and I can type equations into the y= section, but when I press graph the app exits and crashes. I admire the attempted resemblance and similar button layout af a typical graphing calculator, but the fact is it didnt even graph my equations. Complete waste of my 99 cents.

cyfairstudent24 about RK-83: Scientific Graphing Calculator, v1.2.4