Loading sequence:
The folders inside CMBN/data/z/ are arranged alpha numerically and load in sequence from top to bottom. For example: effects, guns, terrain, uniforms, vehicles. Sub-folders within each of these are likewise arranged alphabetically.
Note, that a sub-folder within the folder 'guns' will load before any sub-folder within the folder 'uniforms'.
No matter how many layers of sub-folders there are within 'guns' these will always load before any folders within 'uniforms'.
As mentioned by Badger73, check for the presence of mod-tags both in the scenario (use the editor) and the mod and check the loading sequence. I would add to that the question, are your uniform mods the current 'smod_' type or the older non-'smod'? They should be the newer. Are they '.bmp' files?
If you are installing them as '.brz' you might need to unpack them to check.
Are you installing them using JSGME? If so, have you configured it properly to install the mods into CMBN/data/z and do they appear lower in the list than any other folder containing uniforms of the same name (replacing the latter is okay too)?