drupal :Plagiarism Checker - Authentication Framework module not working

I am new to drupal. When i enabled the module i got tabs. when i selected google tab i got this error: warning: Parameter 2 to _auth_confirm_page() expected to be a reference, value given in 开发者_如何转开发D:\wamp\www\drupal-6.19\includes\form.inc on line 376.

plus i don't understand where i have to give the google api key.

the module is available here

You need the PEAR class Text_Diff, see the following:

http://pear.php.net/manual/en/installation.php.

http://pear.php.net/package/Text_Diff