Maintence.php Error

When running the maintenance module in admin, pilot hours all show 1 hour, and this error at the beginning of the run:

/core/common/StatsData.class.php on line 171

169 public static function getMonthsSinceDate($start) {

170

171 $key_month = date(‘MY’, $start);

172 $key = ‘months_since_’ . $key_month;

173 $months = CodonCache::read($key);

This does not help a lot. What do you have on your /core/common/StatsData.class.php on line 171? Can you paste the whole function which has line 171?