weird photo issue

I created an image in Adobe Illustrator (and edited in Photoshop). I saved it as a normal JPG, and sent it to my iPhone to be used as a wallpaper.

I can view the image on the phone inside an email or SMS window.
But.
I cannot set it to wallpaper, and if i save it to camera roll, it shows up as a black image.

Any ideas what i'm doing wrong here?