I'm glad that I'm not the only one who's confused by maya's hirarchy design...
The eyeball controls come of the groups "right_eye"/ "left eye" which come of the head control. things like "upper_eyelid_r" ect. come of the right_eye group, so are just the same level as the eyeball controls...
but thx for your help
didn't work though...

i'm getting depserate here...

Edit: I tried playing around with the aim constraint options and came to the conclusion that with the "World Up Type" to "None" it seems to do what I want... although I'm not sure if it won't give me problems later... but anyway...
If someone's got a better idea, I'll be glad to read it