Error when having not 5xx our 4xx error in log

When you haven’t any error in your apache log file, you’ve got this error :
Use of uninitialized value in addition (+) at ./check_access_log.pl line 152.
Use of uninitialized value in addition (+) at ./check_access_log.pl line 152.
Illegal division by zero at ./check_access_log.pl line 152.

You can fix it with this diff :
diff /tmp/check_access_log.pl.ori /tmp/check_access_log.pl
152,153c152,156
if ( defined $status_score{’20X’} || defined $status_score{’30X’} ) {
> $failure_rate=
> sprintf(“%0.2f”, 100 – (($status_score{’20X’} + $status_score{’30X’})/$lines) * 100.0);
> }

You also need that nagios can access to apache access file