[Serusers] pre_auth(): Credentials with given realm not found

Hi all iam testing Voicemessages with Asterisk in the log i get frequently pre_auth(): Invalid nonce value received, very suspicious ! when i debug, i get the following message i have posted my config couple of day back 5(2213) get_hdr_field: cseq <CSeq>: <6> <REGISTER> 5(2213) DEBUG: is_maxfwd_present: value = 70 5(2213) parse_headers: flags=256 5(2213) DEBUG: get_hdr_body : content_length=0 5(2213) found end of header 5(2213) find_first_route(): No Route headers found 5(2213) loose_route(): There is no Route HF 5(2213) check_self - checking if host==us: 14==13 && [mydomain.com] == [myipaddress] 5(2213) check_self - checking if port 5060 matches port 5060 5(2213) parse_headers: flags=-1 5(2213) parse_headers: flags=-1 5(2213) check_via_address(some ip address, some ip address, 0) 5(2213) check_self - checking if host==us: 14==13 && [mydomain.com] == [myipaddress] 5(2213) check_self - checking if port 5060 matches port 5060 5(2213) parse_headers: flags=4096 5(2213) pre_auth(): Credentials with given realm not found 5(2213) build_auth_hf(): 'WWW-Authenticate: Digest realm="mydomain.com", nonce="44f6ee623e15edb81a22dcec25ebe8c58b6e056d" '