did you find a resolution to this issue. I have come on s'thing which seems v. similar (am testing CGI::Session also):

2 possibilities:

1. create direct connection

my $dbh = ablib::connectMe($pIn{'admUn'}, $pIn{'admPw'});

2. using session->param

my $dbh = $session->param("dbh");

Then I pass in identical way to query sub

my @loopData = ablib::menuSQL($dbh, $myID);

#1 works perfectly, #2 fails on $dbh->prepare(...)

Interrogation of vars and both look ok :

#1 DBI::db=HASH(0x83caa6c)

#2 DBI::db=HASH(0x84b7514)

any ideas ?