Hi after I installed the software when I go my domian , I get the error below

Fatal error: Smarty error: [in header.html line 42]: syntax error: unrecognized tag 'block_lang_selector' (Smarty_Compiler.class.php, line 580) in /users/web/uniweb/web/lib/smarty/Smarty.class.php on line 1088


Anyone please help??