[Old GUI] Buttons on Top not responding correctly on iOS

Hey guys,

the problem I'm facing is that buttons on the upper edge of the screen aren't responding correctly. To explain it better I've uploaded a edited screenshot.

Only the green area is clickable. The Red area opens buttons from the lower half of the screen.. as if there's another screen squeezed in the y.. :/

I'm using a GUI Matrix to scale the GUI. Maybe it got something to do with another problem im facing: http://answers.unity3d.com/questions/845451/gui-matrix-problem-only-on-ios.html

It's really a strange behaviour. I hope that someone has an idea what's going on there.

best regards Dennis

ps. that's a old project and i don't want to change everything to new unity gui