Hello,
In the referred challenge The Check Challenge Button shows me this error message:
"The page does not include a reference to the specified image"

This is my code, and it works fine (shows the kitten1.jpg)
<apex:page >
       <apex:image url="{!URLFOR($Resource.vfimagetest,'/cats/kitten1.jpg')}"/>
</apex:page>

Where could be the error?

Thanks a lot, B.R