I just install this Cross Sell mod but I have some problem with the product_info.php file.

I insert this line in that file

PHP Code:
define('TEXT_XSELL_PRODUCTS', 'Related Products'); 
and upload it to includes\languages\english\mytemplate.

All of the sudden the product page goes blank. What seems to be the problem? It reappears if I remove the product_info.php file. By the way I did installed the module manager mod. I don't know if it has to do with tabbed products pro mod.

Can someone help me on this? Thank you.