Why can PDSysEncodingCreateFromCMapName fail ?

I made several trials to get the PDFL 11 sample

   Samples\SnippetRunner\Sources\snippets\Shared\AddGlyphsSnip.cpp

to run

Whatever i tried, the program always fails at

   PDSysEncodingsysEncoding=PDSysEncodingCreateFromCMapName(ASAtomFromString("Identity-H"));

I use "Identity-H" as i need to workout a real unicode version with glyph indices.

But also using the unmodified  AddGlyphsSnip sample fails at the same line with the encodings defined in the sample.

The reported Error Text is always

   The encoding (CMap) specified by a font is missing.

Does this function anyhow us a global state or why does the message refer to any font?

PDSysEncodingCreateFromCMapName  has only a single parameter definig the encoding.

Did anyone manage to get this sample working using Windows XP x64 with PDFLSDK10.1.1?

Any hint appreciated.