undefined reference to `PgConnection type_info function'

I Get this error message when trying to link my program. All I have is
a "PgDatabase conn(<conninfo string>); ", and "cout <<
conn.ErrorMessage() << endl;" in my db.c++. If there is a library or
something I have forgotten to include please tell ... Compilation was
successfull witout any errors or warnings.

g++ -lpq++ asiagent.o db.o info.o -o
/mnt/home/morimekta/stash/Skole/Prosjekt/asiagent/bin/asiagent
db.o: In function `PgDatabase type_info function':
db.o(.gnu.linkonce.t.__tf10PgDatabase+0x10): undefined reference to
`PgConnection type_info function'
db.o(.gnu.linkonce.t.__tf10PgDatabase+0x1a): undefined reference to
`PgConnection type_info node'
collect2: ld returned 1 exit status

Morimekta (Stein E. Johnsen)