The debug tactics is quite simple: switch debug output on with pd4ml.enableDebugInfo() and check what it dumps to STDOUT. It should be traces that it successfully loaded pd4fonts.properties (by the way, did you generated the file as required?) and the referenced font files.
TTF embedding feature has one requirements to TTF file format: the custom TTFs must be UNICODE-compatible (as almost any modern TTF font).
If for some reasons it rejects your TTFs, you may play with TTF file format using free FontForge utility (you may change TTF file options in “Save TTF” dialog). It is built for UNIX/Linux platform, but also runs on Win32 in Cygwin environment. Just google for a preconfigured FontForge + Cygwin with the following keyword: “fontforge-mingw_2008_11_21“