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?