diff --git a/inc/RRule.php b/inc/RRule.php
index a58110d3..b3ef54b0 100644
--- a/inc/RRule.php
+++ b/inc/RRule.php
@@ -366,13 +366,14 @@ class RepeatRuleDateTime extends DateTime {
       if ( isset($matches[8]) && $matches[8] != '' ) $interval .= $minus . $matches[9] . ' minutes ';
       if (isset($matches[10]) &&$matches[10] != '' ) $interval .= $minus . $matches[11] . ' seconds ';
     }
-//    printf( "Modify '%s' by: >>%s<<\n", $this->__toString(), $interval );
+    if ( DEBUG_RRULE) dbg_error_log( 'RRULE', "Modify '%s' by: >>%s<<\n", $this->__toString(), $interval );
 //    print_r($this);
     if ( !isset($interval) || $interval == '' ) $interval = '1 day';
     if ( parent::format('d') > 28 && strstr($interval,'month') !== false ) {
       $this->setDate(null,null,28);
     }
     parent::modify($interval);
+    if (DEBUG_RRULE) dbg_error_log( 'RRULE', "Modified to '%s'", $this->__toString() );
     return $this->__toString();
   }
 
@@ -837,6 +838,7 @@ class RepeatRule {
       $this->current_set = array( clone($this->current_base) );
       foreach( self::rrule_expand_limit($this->freq) AS $bytype => $action ) {
         if ( isset($this->{$bytype}) ) {
+          if ( DEBUG_RRULE ) dbg_error_log( 'RRULE', "Going to find more instances by running %s_%s()", $action, $bytype );
           $this->{$action.'_'.$bytype}();
           if ( !isset($this->current_set[0]) ) break;
         }
@@ -847,6 +849,7 @@ class RepeatRule {
 
       $position = count($this->instances) - 1;
       if ( DEBUG_RRULE ) dbg_error_log( 'RRULE', "Inserting %d from current_set into position %d", count($this->current_set), $position + 1 );
+
       foreach( $this->current_set AS $k => $instance ) {
         if ( $instance < $this->base ) continue;
         if ( isset($this->until) && $instance > $this->until ) {