NameServers + VPS + 1and1 = Sorry, we couldn't find any name servers

Hi everyone , I'm really going crazy to configure DNS using Plesk (Centos 6.8) + 1and1:

Step 1) I created web spaces in Plesk and created also DNS zones (for each website).
Step 2) I created an A record (for each domain) in the 1and1 admin panel to point to the VPS IP (WORKS)
Step 3) I created an MX record (for each domain) in the 1and1 admin panel to manage email accounts with postfix (WORKS)

I have an issue with NameServers configuration:
a) If I use 1and1 NameServers website is...

NameServers + VPS + 1and1 = Sorry, we couldn't find any name servers