I am using Stackdumps with Win32, to write all return adresses into my logfile. I match these with a mapfile later on (see my article [Post Mortem Debugging][1]).
<
Regarding RtlCaptureStackBackTrace, one thing I've noticed on 32-bit Windows is that it fails if you pass too large a number into it for FramesToCapture. Experimentally I've identified 61 as the maximum value, for no reason that I can fathom!
Not sure if it's the same in x64, but that might explain why you're getting no info out.