can't upload theme "please try again"

When I try and upload the theme, (in wordpress), I get the message :

**Are you sure you want to do this?**

**Please try again.**

I know my file size upload limit is 128 MB, so that’s not the problem.

(I have had success upleading other themes.)

Try using FTP and it should work - 95% of the time that error is a hosting issue