CopyToCD and MP3 files

What is the breakpoint when CopyToCD do not ask you to create an Audio CD and instead writes a data CD?

I have a directory with 73:09 minutes of MP3 files (according to Easy CD-DA Extractor) and CopyToCD treats the request to burn it as a data directory.

Or am i wrong that it has something to do with number of minutes and it instead do not recognise the files as MP3?