First off all dont forget if you use WINRAR that it looks like it is a .rar file.
But it is offcourse a ZIP, so if u use winrar, and you are adding to archive bakc again dont forget to so extension back to ZIP.
And Tremerion, could you please just DON'T post the modifications, but post YOUR OWN maps you have on your harddrive. Then we have the right maps and dont have to do the difficult stuff on our own, for many of us is that too difficult if I read all these posts.