Can i get help with domain mapping

I have followed all the advice in the thread listed below but I can still not get domain mapping working. To make sure I have the right environment I purchased a new dedicated server today and have migrated my Multisite across and applied a dedicated ip, but still no luck. I have clients now waiting for their sites to go live so would live some assistance.
Thanks

https://premium.wpmudev.org/forums/topic/why-is-my-domain-mapping-not-working-1#post-487012