Association View request problem

Hello.
I'm new with Gurux.Net and I'm tring to use the Gurux libraries to read Meter device data.
I tried to develope a little class for manage meter device connection, but I've problem with association view call:

...
GXReplyData reply = new GXReplyData();
ReadDataBlock(Client.GetObjectsRequest(), reply);
Client.ParseObjects(reply.Data, true);
...

I have an exception on ReadDataBlock command:
{"Access Error : Device reports a unavailable object."}

I suppose Client.GetObjectsRequest() didn't return a correct object. I analized the code of the class GXDLMSClient and I found that the object name returned is:

"0.0.40.0.0.255"

I cannot understand which object this command refear:
==> Client.GetObjectsRequest()

I tried to change this name, but I think is not correct.

Probably, my meter, hasn't got these LN, so I cannot execute the association view call.

Shall you help me?

Thanks.