Why was this rejected for IP?

This plaster frame image of Uncle Sam photoed in a public park was rejected for IP reasons.

The frame painting, background and text were modified by me (you can see the difference in text 'to exercise'). Uncle Sam is in the public domain and the likeness in varying shapes and sizeds are used frequently in advertising. So I am not sure why the rejection?  Do I submit a release stating my arguement? Any help would be appreciated.