I Cannot Upload pics to my coppermine gallery!

[mariaxoxo]

Hi! I have a problem. When I upload larger files to coppermine gallery it says this:
Fatal error: Allowed memory size of 20971520 bytes exhausted (tried to allocate 5956 bytes) in /home/hilaryduff/domains/hilary-duff.biz/public_html/gallery/include/picmgmt.inc.php on line 272

And I have checked this theard:
http://coppermine-gallery.com/forum/index.php?topic=24088.msg110690#msg110690
And I have also asked my host to check it out and he did but he told me that the memory limit is already set at 20. So can you tell me what's the problem?

[Nibbler]

20 is obviously not high enough for the image you want to upload. Alternatively resize it yourself or use IM if available.