Can't upload pictures using Paperclip due to weird error

I'm developing in Ubuntu, already have installed ImageScience and I'm
getting this error everytime I try to upload a picture:

[paperclip] An error was received while processing:
#<Paperclip::NotIdentifiedByImageMagickError: /tmp/
stream20090816-10096-ddupoc-0 is not recognized by the 'identify'

Can someone guide me on a solution?