Perl DBI and postgres

This is probably just a general DBI question but I get the following
errors when I run my code:

DBD::Pg::st fetchrow_array failed: no statement executing at ./snap.pl
line 110.
DBD::Pg::st fetchrow_array failed: no statement executing at ./snap.pl
line 110.

Line 110 is a disconnect statement:

$target_dbh->disconnect();

I have multiple functions which access a target database, take the
information and put it back into a repository. They all follow this
format, the database handlers are passed in, statement handlers are
created and closed at the end of the function.

sub free_space {

my $err=0;
my ($repo_dbh, $target_dbh, $snap_id) = @_;
my $target_sth = $target_dbh->prepare(
q{ SELECT columns
FROM the table }) or "Can't prepare statement:
$DBI::errstr";
$target_sth->execute() or die $DBI::errstr;

while (my ($data) = $target_sth->fetchrow_array()) {
eval {
$repo_sth = $repo_dbh->prepare("INSERT into thetable
(columns)
VALUES (?, '$data')");
$repo_sth->execute($snap_id) or die $DBI::errstr;
};
}
# check for errors.. If there are any rollback
if ( $@ ) {
$err = 1;
}

$repo_sth->finish();
$target_sth->finish();

return $err;
}

The main function just opens connections to the repository and target
database and closes them at the end with disconnects and that is where the
error is occuring.

Any ideas?