MU set up ,EC2 ,Multi-Domain not working probably

Hello There,
After lots of efforts and setting up Wordpress in EC2,AWS and following all the steps including permission issue I have a this problem.

I have installed Multi-site AKA multi domain as auto install and when I'm adding a new site (whose domain is pointed to the static AKA elastic ip address) instead of opening like for log in it goes back to the main site i.e and I am wondering should I create a mu-plugin and install the multi-domain in there or is there any thing else I'd have to do ?
Many thanks in advance.