Frameless Showerscreen problem

[jazzcricket]

Hi i'm trying to fit a showerscreen, pretty much the same as the one below.
I've drilled the holes in the wall channel,and the tiles, and fixed the wall channel to the wall.
The problem is when i try to slot the screen into the wall channel.
It simply won't go in, and it looks like the 2 screws top and bottom are not lined up properly with their respective holes, or that they are stopping the screen from going into the wall channel itself.

I'm at a bit of a loss, would appreciate any ideas.
[youtubehttp://www.youtube.com/watch?v=TiBxTsP-nZ4&feature=player_detailpage][/youtube]

 

[foxhole]

Maybe upside down?
Or screws may need to be loose before it's offered up.

 

[jazzcricket]

Maybe upside down?
Or screws may need to be loose before it's offered up.

Thats what i thought, so i flipped the wall channel upside down, but it made no difference.
The screws are loose, but i can't remove them completely which i thought might have solved the problem.