If you want to use Openprovider for a slave nameserver for you own nameservers, it is necessary that Openprovider can read the data from your master nameserver. You have to configure your master nameserver, allowing IP address 126.96.36.199 / 2a00:f10:121:400:4be:60ff:fe00:526.to read your zone files and do zone transfers (AXFR). Only in this way, the records can be copied.
You can check whether this is the case, by choosing in the menu DNS management - DNS Checks the option Possibility to use slave nameserver at Openprovider. Enter the domain name and the IP address of your master nameserver, to see the result of the check.
How to configure this depends on your own DNS server software. For our customers that use the Plesk control panel, you can configure this in the menu Server - DNS - Common ACL. The IP address that will read your master nameserver, is 188.8.131.52 / 2a00:f10:121:400:4be:60ff:fe00:526.