drivers side fornt window replacement

i have a 1991 pontiace grandprix 4 door. the drivers side window shattered when i shut the door. i bought a new window for it and have it installed. one problem is when window goes down its fine. but when u go to raise it it seems to want to jam and try to go up croked.i checked the door iner rail and it seems to be straight and not bent. any help with this would be very much apriciated. it has electric windows .

There is supposed to be a triangular plastic piece that rides in the rear channel that is hooked to the window to keep it level, is that piece still there?

yes its there and its in the track . the window goes down fine but starts back up and binds .