Board Thread:Support Requests - Getting Technical/@comment-4093403-20130628124005

I was trying to promote my wiki using the  Special:Promote page, but when I tried to upload an image, it said that there was an unkown upload error. The page says that I should upload an image that is a png file and minimum 480x320, but my image is a png file and 1480x1076, and it still doesn't work. I don't know what is wrong. 