[TYPO3-dev] What is wrong here?

[Christopher]

Hi there,

I tried to change some code (in class.t3lib_beuserauth.php, lines 188 
following), but now I get an error.

Original:
if (...) {...
    t3lib_BEfunc::typo3PrintError ('Login-error or session 
timed-out',.........
    exit;
   }
  } else


New:
 if (...) {...
   t3lib_BEfunc::typo3PrintError 
($GLOBALS['LANG']->sL('LLL:EXT:lang/locallang_core.xml:beuserauth.loginErrorSessionTimedOut'),....
   exit;
  }
} else

Error is:
Fatal error: Call to a member function sL() on a non-object in 
/typo3_src-4.2.0/t3lib/class.t3lib_beuserauth.php on line 192

Question is: How do I correct this?