sunroof problem

ok so my 08 grand prix gxp's sunroof is acting retarded, it works normally when i open it but when i close it it dosnt stop and pops the back up. it normally automatically stops when it is closed but recently started doing this. is there a stop switch that can be adjusted or something? how do i fix this?

there should be two hooks / notches that catch the sunroof and keep it from going into the vent position, could be an issue with them.