[SR-Users] Registration Failure

Hello, I'm a new starter of Kamailio (SER). I am using the version 4.4.0-dev6 in a Debian machine. I've configured all the IMS network elements, the FHoSS and also Boghe IMS/RCS client in a Windows machine. When an IMS user belonging to my network tries to register and IP SEC mechanism is enabled, the registration flow stops at 401 Unauthorized from S-CSCF -> I-CSCF -> P-CSCF -> client. The problem is that the HSS in MAA message does not send the SIP-Auth-Data-item that should be cointain the Confidentiality Key and the Integrity Key; so the client is not able to challenge the S-CSCF sending another REGISTER message. Do you have any suggestions about this? When IP SEC is disabled (by managing client options), the registration works well. Maybe is there any configuration at HSS level that i'm not considering? Thank you in advance for your help, Cristina