pst_status record problems

Hi There,
We've been creating a little program that collects all the performance data available about the processes on a HP-UX system. (running HP-UX 11.11).

And everything works fine apart from 4 fields in the middle of the pst_status record.

Input Blocks (pst_inblock)
Output Blocks (pst_oublock)
Voluntary Context Switches (pst_nvcsw)
Involuntary Context Switches (pst_nivcsw)

These fields contain the same value across all the processes, which is incorrect.

Has anybody else tried getting this data? Did you have the same problem?

Cheers
Phil