Forwarding working to subdomain but doesn't mask with new URL

• I am trying to use Domain Mapping to assign a URL to a subdomain on my WordPress Multisite. The domain is traviscountycourtsteam.com and the subdomain is proposal.zandercurtis.net.

• The forwarding works but I can't get Domain Mapping plugin to accept the URL. When I go into the Domain Mapping plugin TOOLS for the site and click the MAP DOMAIN button it just says "Domain name is unavailable to access." The DNS Check shows the domain servers are propagated.

•The goal is for it the URL to show traviscountycourtsteam.com NOT proposal.zandercurtis.net.

• Is there something else I should be setting?