When using a USB loader to play Cod games you need to use a cIOS with a 57 base.
Standard setups use 250, but it may be different on your setup depending on what guide you used.
On page 4 of ModMii classic (blue background white text), http://modmii.zzl.org/ , type rec, to select the recommended cIOSs, then d to start downloading them.
or install cIOS 202-251 from wiihacks guide, http://www.wiihacks.com/recommended-faqs-guides-tutorials-only/96886-guide-softmod-any-wii.html , found in the modpack download. The cIOS 9,11,20,30,50,60,70,80,&90 are System Menu wads, i suggest you stay away from them if you don't know what you are doing.