Domain Mapping plugin several problems

I have several problems.
Using the plugin locally (with DNS emulations and hosts files all works properly)
BACK END:
> i add the choosen domain to map (www.mydomain.com) and allways i get "invalid staus". I setted the domain as follow:
mydomain.com A 185.21.xxx.xxx
*.mydomain.com A 185.21.xxx.xxx
(xxx it is just to hide real ip here)
> on the web server mydomain.com is mapped to the same wordpress doc root
> if i try to disable the dns check (it allow me to add domain as invalid), i relate it to my subsite.domain.com and then i call in the browser: http://www.mydomain.com i have the error: Internal Server Error (as setted up subsite.domain.com redirect to http://www.mydomain.com)
> if i disable the the mapping erasing the list of the associated domains to map,
subsite.domain.com work properly. http://www.mydomain.com give me the samer: Internal Server Error

Please let me know
as soon as possible

Thanks a Lot