Nested Query OK in psql but not in PHP

I have a nested query that runs fine in psql but does not return
tabular data in PHP. I have built the query a step at a time and it
works as expected, even in PHP up to the point where I include the
second query, which uses a concatted string of field data to provide
row identity. I'm quite the PHP newbie in mysql and even moreso with
postgresql. Is there something that changes in the PHP code that builds
the tabular display if a query is a nested query as opposed to it not
being a nested query? I get no errors in /var/log/messages so
_something_ thinks the query is OK. I'm just not seeing a populated
table; only the html-coded column headings.

I can include some actual cut-'n-paste, but I'd like to try and figure
at least some of this out myself first.

Regards,

r