Fatal error: Uncaught TypeError: Unsupported operand types: string - int in /customers/b/d/3/goethe-verlag.com/httpd.www/database/common.class.php:249 Stack trace: #0 /customers/b/d/3/goethe-verlag.com/httpd.www/book2/index.php(67): clsCommon->funcGetSelectLessonName('BG', '___') #1 {main} thrown in /customers/b/d/3/goethe-verlag.com/httpd.www/database/common.class.php on line 249