How to properly invoke KeyAgreement

Hello,
I'm trying for past few days to use keyAgreement method from SecuritySetup to agree on keys on multiple meters from different vendors.

So far all my attempts resulted in error: Other reason.

I also tried multiple small changes to the library itself. I think I found out, that currently keyAgreement in security setup does ignore the Security Suite and uses only P256. The keyagreement method should be working with P256 and also P384 automatically, so it probably needs to be adjusted and also the GXSecure.getEphemeralPublicKey methods, to create the signature corectly.

I understand all keyagreement related code, except the signature byte buffer creation in GXSecure.getEphemeralPublicKeySignature()

This is what I do when trying to invoke the method:
I have open working connection even authenticated using HLS-ECDSA, so signing certificates are correct.

//Generate Ephemeral Keys, I tried both P256 and P384:
ciphering.setEphemeralKeyPair(GXEcdsa.generateKeyPair(Ecc.P384));

//Setup again the signing keys, to be sure:
ciphering.setSigningKeyPair(new KeyPair(
                   getServerSigning().getPublicKey(),
                   getClientSigning().getPrivate()));
                    
//create the message:
message = securitySetup.keyAgreement(getClient(), keyType);

//send the message:
GXReplyData reply = new GXReplyData();
reader.readDataBlock(message, reply);

Currently it ends up with other reason. I would like to also know: when everything is correct, do I need to do something with the keyAgreement when response is recieved? Or it will be handled automatically in the reader and "readDLMSPacket" method, which calls dlms.getData().

Thank you for the response.