Towers
I have an Epon printer, so I don't know if this is will be the same for the Canon, but I found that I had to set the printer manually to "print to disc" in order for the Labelprint software to recognise the printer.
I like the software, but my current dissapointment is that Labelprint will not work with full face printable discs, and the Tech Department don't seem to be interested in a patch. (when I say won't work with full face printable discs I mean that it will only print to the inside diameter of a standard disc)
Tom