cmap for this font is missing

I wrote some code using the following  PDF API call

            encoding = PDSysEncodingCreateFromCMapName(cmapAtom);

This throws an exception

The CMAP for the existing font is missing or something that effect. I am using UniJIS-UTF16-H as the CMAP designation and ArialUnicodeMS for the font.

I have the PDFLDataRec data structure set up to look for the resource directories that contain the information, CMAP,Font, Unicode, but this doesn't help.

I cal PDFLInitHFT() to pass this information to th PDFL API library to initialize it but it doesn't seem to help. What am I missing?