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Ok... not sure if this resolves the issue for brigitteserr but just some general tips.

The Scan button will only work if you have installed a suitable scanner based software packed on your computer. As a general rule this is the Navigator software for your Canon model as provided with your driver disk (or on the Canon website).

Personally I would recommend that instead of using the scan button on the printer, you initiate any scanning from your software and then work from there as all the scan button does is initialise the program and nothing else.

Hope that helps.