.w3x maps will not load in WC3's map list, why not?

[orion-]

Hey,

I've been installing some custom maps from various sources and I'm having a big problem; I install say "custommaulmap.w3x" into my "download" folder, like with all my other custom maps, but the maps don't appear in the custom map list in Warcraft 3 RoC, why is this?
I've noticed some of the maps are .w3m, they seem to work, but .w3x formats don't. Why is this? anyone had problems like this before?

Thanks guys, hope somone can help me out !

(ps. i've tried this with old and new maps, they both don't load. so it's not a problem with the map being out of date or anything.)

[x42bn6]

.w3x files are Frozen Throne maps and hence will not work in Reign of Chaos.*