[Serusers] serctl failure + authentication

folks i'd appreciate if i could get some pointers re: following incidences... 1. my attempts to invoke serctl to add a new subscriber fail [error: 400; check if you use aliases in SER] at all times which suggest i must be doing something wrong. 2. when i enable the authentication code block in ser.cfg, my 1st registration attempt fails with a response type of 401 (unauthorized) which contains a WWW-Authenticate header. subsequently, my ua (x-lite softphone) sends another register message which contains an Authorization header with some number of credentials. unfortunately, this 2nd attempt also results in a 401 response. are there certain things that i should do on the client/server side to get ser authentication to work? thanks for your help in advance, gurol