Domain Mapping plugin - cpanel difficulties

I've purchased the plugin and installed it. I get stuck on the CPanel part. My Cpanel won't allow me to park a domain (I either get an error saying the domain is already configured or that I'm not allowed to add (0) parked domains).

So I tried to do an A record. But when I go to set up an A record, CPanel automatically adds my original domain to the TLD I'm trying to add.

So I want to have a TLD of
When I enter in the A Record form, it automatically makes it Is that right?