SQL date calculation problem

Hi all,
I using postgresql 7.1.3 on RH 7.2 server. I am having trouble with
TIMEDATE calculation using the pgplsql procedural language the logic is
has follows:
FOR r IN SELECT time_span FROM t WHERE name = ''NEW'' LOOP
NEW.end_date := r.time_span + now();
END LOOP;
When I try running this routine I get an error "Bad timestamp external
representation '11:39:09' ". This routine ran in previous versions of
postgresql does any one have any ideas.