If the light is flashing very likely the medium is not set to "CD printable".
Choose the media type "CD printable" in your application (if media type setting available in application) or change the default in TurboPrint Config / command line "xtpconfig".
If you are printing from GIMP, you must choose medium "CD printable" and page size "CD" in TurboPrint Config as defaults.
See also the TurboPrint HTML manual, chapter 9 section "printing on CD/DVD". The manual can be opened with the "Help" button or directly from /usr/share/turboprint/doc/html.