dashboard: Fix crash getting data for plots

include/ajax.reports.php

@@ -19,6 +19,7 @@
 if(!defined('INCLUDE_DIR')) die('403');
 
 include_once(INCLUDE_DIR.'class.ticket.php');
+include_once(INCLUDE_DIR.'class.report.php');
 
 /**
  * Overview Report
@@ -174,11 +175,7 @@ class OverviewReportAjaxAPI extends AjaxController {
             $stop = $this->get('period', 'now');
         }
 
-        if ($start != 'last month')
-            $start = DateTime::createFromFormat($cfg->getDateFormat(),
-                $start)->format('U');
-        else
-            $start = strtotime($start);
+       $start = strtotime($start);
 
         if (substr($stop, 0, 1) == '+')
             $stop = strftime('%Y-%m-%d ', $start) . $stop;