The use of “cupsaddsmb” gives “No PPD file for printer...” message while PPD file is present. What might the problem be?

Have you enabled printer sharing on CUPS? This means, do you have a <Location /printers>....</Location> section in CUPS server's cupsd.conf that does not deny access to the host you run “cupsaddsmb” from? It could be an issue if you use cupsaddsmb remotely, or if you use it with a -h parameter: cupsaddsmb -H sambaserver -h cupsserver -v printername .

Is your TempDir directive in cupsd.conf set to a valid value, and is it writable?