Mapping usernames for local/loopback connections

Hi,

I'd like to use the following in pga_hba.conf:

local   all             all                                     trust map=mymap
host    all             all             127.0.0.1/32            trust map=mymap

where pga_ident.conf contains

mymap jan dbuser

With this setup in place, the server is not started (and since I don't know how to turn on debug mode for pg_ctl, I
don'tknow why). 

Could anyone point me in the right direction?

Thanks a lot,
Jan