custom grouprule

Hi I have a group field for entry of a time hh:mm. I want to validate the time but am not sure how to access the values it is passing to the function. $eventform->addGroup($eventtime,'eventtime','Event Time (hh:mm)',':'); // Add the rules to the group $eventform->addGroupRule('eventtime',array($hour_rules, $minute_rules)); $eventform->registerRule('timevalid','function','valid_time'); $eventform->addGroupRule('eventtime','Invalid Time', 'timevalid'); function valid_time($element_name, $element_value) { echo "inside valid time"; $isValid = true; echo "this is element name " . $element_name; echo "this is element value " . $element_value; } It only appears to be passing the minutes, not the hour. Any assistance would be appreciated. Thanks Andrea