Prototyped Call to 3rd party software

I'm in trying to call 3rd party program with CALLP. When I compile the
program I get errors stating that errors were found during the binding
step. I'm already binding to the QC2LE directory for other prototypes
I'm using so that might be the problem. 

I'll most the prototype definition and the callp statement that I think
is causing the binding errors. I can't /COPY the source member for PROG1
and it is an OPM program. 

 

H dftactgrp(*no) bnddir('QC2LE')

 

D Call3rdPty       PR                  EXTPGM('PROG1')

D Parm1                        8

D Parm2                        2P 0

D Parm3                       10

/free

 callp Call3rdPty(val1:val2:val3);

/End-free

 

Can anyone see what I am missing?  Should I use QCMDEXC or SYSTEM
prototype instead?