BMW X5 E70 Sunroof opening problem

[mechan]

Hi, I have the car 2007 x5. There is a sunroof opening problem. When I push the button, then both sunroof glasses can open with an angle. But If I want to open completely, Im hearing a noise like mechanism is trying but can not open. This noise is coming from motor. It means sunroof motor is working. Big front glass opens 1-1,5cm from left side. When I want to close again, it can not close. While I push the button, and at the same time I support my hand inside of the car for using little bit force to up the glass, then the glass can close..

I dont understand guys what is the main problem.. Can you pls help me about it? thank you so much..