Ee-D Focusing Screen Install Help

I'm trying to install a Ee-D Focusing screen on my 5D. I followed the instructions to the letter, including making sure the tab is on the right side, but I can't get the focusing screen holder to close. I even tried to reinstall the original screen and I still can't get the holder to close. Is there some trick I'm missing here? I'm desperate since I need to use the camera in a few hours.

Thanks.

Never mind, i got it installed.

I had to use a bit more pressure than I thought was necessary and also use my left thumb to depress the screen holder release but it worked. Phew!!!

Check your custom functions...you may need to set it for the new focus screen...this will keep your metering accurate.