correct way to call dns_ptr_update?

Hi. Following this, https://fossies.org/linux/ISPConfig/remoting_client/API-docs/dns_ptr_update.html
I coded my program.. The previous PTR record was like:
65.109.18.75 86400 PTR usa-mythos.com.
My aim was to change the IP address, so I did it like this:

Code:

     $newdata  = $new_ipv4;
                           $params = [
                               'server_id' => $record['server_id'],
                               'zone' => $zone_id,
                               'name' => $record_name,
                               'type' => $record_type,
                               'data' => $newdata,
                               'aux' => $record['aux'],
                               'ttl' => $record['ttl'],
                               'active' => $record['active'],
                               'stamp' => $record['stamp'],
                               'serial' => $record['serial'],
                           ];
                           $client->dns_ptr_update($session_id, $client_id, $record_id, $params);

but that caused the PTR entry to become this:
65.109.18.75 86400 PTR 22.33.44.55
So, what's the correct way to obtain
22.33.44.55 86400 PTR usa-mythos.com.
? Thanks!

 

Many thanks!