Why can't I upload my GIF to Tumblr?

I made this gif yesterday but when I try to upload it, it freezes and doesn't play. It meets all of Tumblr's requirements, so I don't understand what i'm doing wrong. All the configurations I used are below the cut.

I use ImageReady 7.0




498 x 255, 372k, Colors: 135
GIF
Perceptual
Pattern

Thanks for any help! :)