Persistent CGIDEV2 problem

I am using CGIDEV2 (in persistent mode) for the first time and thought that
I was making reasonable progress but have now run against a problem for
which I need help, although I am sure that it has been solved many times
before.

My cgi program is RPGLE and is a request processing program (I will call it
RPP) that handles 5250 or HTML/Javascript output. It does not have any
direct database access but calls a second program (I will call it MAIN).
This handles business logic and reads records and passes them back to the
RPP which displays them using 5250 or CGI. In CGI mode, the first call by
RPP of MAIN works OK and the records are displayed by RPP using wrtsection.
When I type something on my HTML display, the RPP is reactivated correctly
so my Handle is presumably OK and I can read what I typed using
ZhbGetInput. However, when RPP calls MAIN again so that that program can
retrieve the required records, a new instance of MAIN is called. I am sure
that in the first call of MAIN I did not set on LR and the mechanism works
fine in 5250 mode I imagine that this has something to do with activation
groups.

Can anyone help please? I have tried compiling MAIN with the same named
activation group and binding directory as RPP but this did not help.

Many thanks