Unable to upload apk file in Server

I built a simple app for my website and now i want to upload the app on to my server but it does not seems to be uploading there is no issue with other type of files though the it shows uploaded 100% but the directory remains empty.
Please Help.

Zip it up first. .zip

hmmm why is it like that

Security.
Abusive users will upload malware in .apk file and it is easier to call a .apk and install it than call .zip, extract, install before a user notices etc.

Oh now I get it thank you for your timw