Issue ServerShield Cloudflare not working with domain alias

[MaurizioP]

I've enabled the ServerShield extension, and it's working with www.domain web sites, but I can't let it work with domain aliases.

I have domain-a that is working under Cloudflare, and domain-b that is configured in Plesk as a complete alias of domain-b. Before enabling Cloudflare, www.domain.b was correctly redirected to www.domain-a, but now when I go to www.domain-b I got this error:
Error 1016 Ray ID - Origin DNS error

Thanks