CALLPRC with RTNVAL

["Phil" <sublime78ska@xxxxxxxxx>]

I'm having trouble with the data returned from a srvpgm which is called from
a CL with CALLPRC:

     PGM        parm(&parm)
     dcl &parm *char 121

     if cond(%sst(&parm 1 1) *eq ' ') then(do)
       chgvar &parm value(' ')
       callprc prc(getParm) rtnval(&parm)
     enddo

The srvpgm (RPG) returns the correct data, and works fine when called by an
RPG pgm.  The srvpgm exports the parm.

The problem is the value of parm is not correct.

Can anyone tell me what I've got wrong?

Thanks,

Phil