White screen with domain mapping plugin

Hey I have the domain mapping plugin installed and I an trying to map the domain name nixiebird.tk to garethsworld.com/dev. At the moment i just get a white screen.

Sunrise.php is installed at /wp-content/ and it is defined in the correct location in my wp-config.php

My site garethsworld.com is on a server at and when i ping nixiebird.tk i can see it is heading in that direction both an @ and www record are setup pointing there

Finally, in the admin section of garethsworld.com/dev i have made the config chages there.

It is worth noting that i had this working a couple of weeks ago and now it's not

Can i get a hand please?