pgpool question

I'm experimenting with pgpool 2.51 on my Linux box runnung
two postgresql backends: pg74:5432 and pg801:5433

I configured pgpool to use pg74:5432 as primary backend and 
pg801:5433 as second one. Pgpool is running on default port (9999) and
I configured my web application to use it, so I could start/stop backends
without disturbing client (web browser).

When I stop primary backend (pg74:5432) pgpool switched to backend    failover from (5432) to (5433) done
but when I start primary and stopped secondary backend pgpool
never switched back to primary backend as expected ! 
I see bogus message like:    starting failover from (5433) to (5433)

What I'm doing  wrong ?
    Regards,        Oleg
_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83