Thread:Project:Support desk/Can't enable skin Vector.php/reply (5)

Your change in Vector.php looks strange: __DIR__ is defined since PHP 5.3 at least. If you have PHP 5.6, this change should not be needed and if you have an old PHP version, you should get a different error ("Use of undefined constant __DIR__...").

For the blank page, you should check the error log or have your host tell you, what after such error is inside.