Missing mailbox field


I am new with Asterisk and I have following issue.
When user receives new voicemail Asterisk doesnt send SIP Notify msg.
Also I found by sip show peer 6002 that Mailbox field is blank. I have configured this user with mailbox and when I call mailbox access number I can listen messages left for 6002.
I am using asterisk GUI also.
What am I missing? Why notify doesnt work?

thank you