Many users struggle with configuring image support. The sad thing is that Ubercart does most of the leg work for you, and you're still faced with missing images. The problem here is generally a server issue. Here are a few pointers to run through:
- Make sure you've actually configured image support properly. Review this FAQ if you're not sure if you've done this yet.
- Make sure you've enabled Clean URLs on your site. This technically shouldn't be a problem with more recent versions of Image Cache, but you never know. It's good to use clean URLs regardless.
- Double check your files directory settings. You must be using a public files folder, and you have to have created it with the appropriate world read/write permissions required by Drupal.
- Your web host may have some server or .htaccess settings preventing files from being created or accessed. One user received this notice and was provided with this work-around. While I disagree with their statement that Drupal doesn't conform to hosting security standards (notice their recommendation was to ignore a security comment!), this may work for you. You can always contact your host if you have some other problem... that's why you pay them.
If none of these solves your issues, please please please search the forums for existing solutions before posting a new thread. Many users have posted on this issue in the past and found their problems to be unrelated to Drupal and/or Ubercart. We simply can't debug or provide documentation on all the cases. Thanks!