Is your wicked whims up to date? Depending on how long you've been fighting this issue, WW might have broken with the last update and something isn't fixed yet. If multiple pose packs from the creator aren't showing up, that would have me suspect you're missing a necessary support mod / plug-in. Lmk if it works, and if it doesn't, I can try and help you track down a copy. But I'd do the above first if you haven't. If it's still not working, the file you received is bad. Test and see if that mod shows up, then, as you shouldn't have any conflicts. What I'd do for that if you're like me and have a fuck load of mods is to create a guest desktop profile on your comp, install the sims, and put JUST the pose pack and any required mods like wicked whims that make the mod work. If it doesn't, you may have a mod conflict.
Have you tried re-downloading the mod files? Can happen when you're copying / extracting a mod file to your mods folder, so if you haven't, delete the mod from your mods folder and recopy and past into your folder.
It sounds like you either have a bad file download or a conflict.