install domain mapping not working

I proceeded to install the plugin "Domain Mapping" as described in the manual, on the administration panel I have this error message:

When I fill the field and change the dns redirection is not done properly and I get on this page :

screenshot dns a registar :

screenshot configuration :

configuration :

wordpress 3.8 multisite
Server Linux
Parallels Plesk 11.5.30 (64 bits)

Is that I forgot a step?

Thank you for your help