My scanner shows up, but doesn't scan. What do I do?

There are many potential causes for this, depending on the scanner. Some of the suggestions below may help.

• Try switching between Memory Based Transfer and Native Transfer in the Preferences; some scanners work better one of the options.
• Try changing the scanner resolution.
  
• Make sure you scanner drivers are up to date.
• Try scanning using the Image Capture application found in /Applications.