Thanks, Ian.
Tried the test data. Same error/failure.
I just checked out the git version of h5mma; the README seems mostly
about the use of the utility in general, rather than installation
instructions (I'm thinking of things like the prefix chosen at
configuration stage). Should I build directly in the
/Library/Mathematica/Applications directory (sounds wrong), or buld
locally and move the result?
There is a link in the README to the BitBucket wiki, which contains a link to the compilation instructions. This could be easier to find :)
On Mac OS, you shouldn't need to change any prefixes etc, if you are using homebrew or macports.