Sony Ericsson Z750i Help.

I cant seem to remove the back cover of my Sony Ericsson Z750iphone. I have had it for about a year now and have never been able to do it. Is it possible to remove?

http://www.sonyericsson.com/cws/down..._9984_2_12.pdf
Users Manual.
Page 5 states that the cover is just suppose to slide down, then comes off.

Hey I know what you are saying but it quite easy... the Trick is to close the phone and put both thumbs near the top where it clips on for example if you are looking at it from the back fully closed, the green sony ericsson symbol should looking outwards... now all you do is lightly push out(or down) towards the the direction where the symbol is and "POP" there it is!!!! let me know how it worked out!