Error with Screen Function

My code:

"HideCursor; screenNum=2; [window, rect] = Screen('OpenWindow', screenNum, 1); [X,Y] = RectCenter(rect); FixCross = [X-3,Y-40,X+3,Y+40;X-40,Y-3,X+40,Y+3]; disc1 = [X-80,Y-80,X+80,Y+80]+250; disc2 = [X-80,Y-80,X+80,Y+80]-250; disc3 = [X-80,Y-80,X-80,Y+80]-100; Screen('FillRect',window,[200,200,200], FixCross'); Screen('FillOval',window,[200,200,200], disc1'); Screen('FillOval',window,[200,200,200], disc2'); Screen('FillOval',window,[200,200,200], disc3'); Screen('Flip',window);"

I'm not sure but for whatever reason disc1 and disc2 will appear, but disc3 will not. It either just doesn't appear or sometimes I'll get an error message regarding the [window, rect] line.

Any ideas as to what is wrong?

Thanks, Brett

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup

[Jan]

Sometimes? We cannot guess the difference, but you can check it. If you mention, that you get an error, post the complete error message here. It is simply a good idea to make answering as easy as possible.