If ya did folow these steps
1)Replace bitmaps.map
2)Drag aotcr.textures.required.ppf on to ppf-o-matic.exe
3)Click on the disk next to the ISO File blank
4)Go to your Halo maps folder in the window that pops up
5)Under File type select All Files (*.*)
6)Click on bitmaps.map and click Open
7)Click the Apply button
8)Open Halo
9)Click Multiplayer then Internet
10)Click Get List
11)Find a AOtCR MP server
12)Play!

If this doesn't work replace the carousel.map with the one in the rar file again or re-download it (maybe you got a corrupt rar file).