Custom WPP trace format


I’m trying to add a custom tracer for FILE_ID_128, but can’t get it to work…
This is what I have in the INI file:

WPP_FLAGS(-DWPP_LOGFILE_ID_128(x) WPP_LOGPAIR( (16), (x)));```
   and in the driver code, I trace it with: %!FILE_ID_128!, with the address of the FILE_ID_128 struct as the parameter to trace.
   But not only is it (almost) always just outputting 0 (not even 0x0), it is also displaying some garbage in the trace line:
   000/ Some text ? << (the ? is garbage)

   Am I missing something simple here, or need to use a larger font?

Regards, Dejan.