diff --git a/timesheet/inc/class.uitimesheet.inc.php b/timesheet/inc/class.uitimesheet.inc.php
index 7e1efd5d26..56a79cd8f0 100644
--- a/timesheet/inc/class.uitimesheet.inc.php
+++ b/timesheet/inc/class.uitimesheet.inc.php
@@ -91,7 +91,7 @@ class uitimesheet extends botimesheet
 			{
 				$content['ts_start'] += $content['end_time'] - 60*$content['ts_duration'];
 			}
-			if ($content['ts_duration']) unset($content['end_time']);
+			if ($content['ts_duration'] > 0) unset($content['end_time']);
 			// now we only deal with start (date+time) and duration
 			list($button) = @each($content['button']);
 			$view = $content['view'];
@@ -118,6 +118,10 @@ class uitimesheet extends botimesheet
 					{
 						$etpl->set_validation_error('ts_quantity',lang('Field must not be empty !!!'));
 					}
+					if ($this->data['ts_quantity'] < 0)
+					{
+						$etpl->set_validation_error('ts_quantity',lang('Starttime has to be before endtime !!!'));
+					}
 					if (!$this->data['ts_project']) $this->data['ts_project'] = $this->data['ts_project_blur'];
 					if (!$this->data['ts_title']) $this->data['ts_title'] = $this->data['ts_title_blur'];
 					if (!$this->data['ts_title'])
diff --git a/timesheet/setup/phpgw_de.lang b/timesheet/setup/phpgw_de.lang
index ce5fe15c36..9813694142 100644
--- a/timesheet/setup/phpgw_de.lang
+++ b/timesheet/setup/phpgw_de.lang
@@ -39,6 +39,7 @@ select a price	timesheet	de	Preis ausw
 select a project	timesheet	de	Projekt auswählen
 start	timesheet	de	Start
 starttime	timesheet	de	Startzeit
+starttime has to be before endtime !!!	timesheet	de	Startzeit muss vor der Endzeit liegen !!!
 sum %1:	timesheet	de	Summe %1:
 this month	timesheet	de	Diesen Monat
 this week	timesheet	de	Diese Woche
diff --git a/timesheet/setup/phpgw_en.lang b/timesheet/setup/phpgw_en.lang
index 194f7d237e..2e10e56738 100644
--- a/timesheet/setup/phpgw_en.lang
+++ b/timesheet/setup/phpgw_en.lang
@@ -39,6 +39,7 @@ select a price	timesheet	en	Select a price
 select a project	timesheet	en	Select a project
 start	timesheet	en	Start
 starttime	timesheet	en	Starttime
+starttime has to be before endtime !!!	timesheet	en	Starttime has to be before endtime !!!
 sum %1:	timesheet	en	Sum %1:
 this month	timesheet	en	This month
 this week	timesheet	en	This week