Error:spritecss.main: image : not readable

[rodgerthat]

thank you for taking the time and effort to create spritemapper.
this is exactly what we have been looking for,

unfortunately i am having a slight problem,

i'm specifying configuration options inline in the css,
i only have one folder of images,
but i keep getting this error:

ERROR:spritecss.main: ../go.jpg : not readable

i've checked my file paths and everything seems to be in order.

any thoughts?

ty again for your work, it's a really great tool and we'd love to use it in our production work,

[rodgerthat]

tyty to Ludvig Ericson for the catch,
There was some trailing whitespace in my url() for the background images,
url(../images/sprites/whatever.jpg )
vs
url(../images/sprites/whatever.jpg)
it was getting picked up by the parser as part of the filename.