--- egroupware/calendar/inc/class.calendar_ical.inc.php
+++ egroupware/calendar/inc/class.calendar_ical.inc.php
@@ -3433,13 +3433,13 @@
 	public function aggregate_periods(array $events, $start, $end)
 	{
 		// sort by start datetime
 		uasort($events, function($a, $b)
 		{
-			$diff = $a['start'] < $b['start'];
+			$diff = $a['start'] - $b['start'];
 
-			return !$diff ? 0 : ($diff < 0 ? -1 : 1);
+			return $diff == 0 ? 0 : ($diff < 0 ? -1 : 1);
 		});
 
 		$fbdata = array();
 		foreach($events as $event)
 		{

--- egroupware/calendar/inc/class.calendar_groupdav.inc.php
+++ egroupware/calendar/inc/class.calendar_groupdav.inc.php
@@ -867,16 +867,15 @@
 			if (count($content_type) > 1)
 			{
 				array_shift($content_type);
 				foreach ($content_type as $attribute)
 				{
-					trim($attribute);
 					list($key, $value) = explode('=', $attribute);
-					switch (strtolower($key))
+					switch (strtolower(trim($key)))
 					{
 						case 'charset':
-							$charset = strtoupper(substr($value,1,-1));
+							$charset = strtoupper(trim($value));
 					}
 				}
 			}
 		}
 
@@ -1076,16 +1075,15 @@
 			if (count($content_type) > 1)
 			{
 				array_shift($content_type);
 				foreach ($content_type as $attribute)
 				{
-					trim($attribute);
 					list($key, $value) = explode('=', $attribute);
-					switch (strtolower($key))
+					switch (strtolower(trim($key)))
 					{
 						case 'charset':
-							$charset = strtoupper(substr($value,1,-1));
+							$charset = strtoupper(trim($value));
 					}
 				}
 			}
 		}