Can't upload my SWEP I made :(

I created a SWEP and wanna upload it but it says it’s not a .zip file, but it is. I tried it with WinZip and WinRar and keeps saying the same. Thanks in advance:D

Whats the SWEP?

How do you mean what’s the SWEP. It’s a Skorpion Vz.61 divided in the folders: Lua, materials, models and sound. Also a .txt file. I already tried to put those 4 folders in 1 folder and then in a .zip file. Didn’t work either.