PPP connection is not established between DUN server(linux + ofono) and DUN client(Win7)

Hi, I am trying the DUN feature of ofono. DUN server: Linux kernel 3.0 and ofono-1.7 DUN client:win7 However, PPP connection is not established between DUN server(linux + ofono) and DUN client(Win7). DUN client(win7) keep at the status of "verifying user and password". The attachment is the log of ofono(DUN server). After checking the log, DUN server(ofono) got the event 7 (RCR-) firstly at ppp_enter_phase() 1. After DUN server(ofono) got the event 8 (RCA), DUN server(ofono) always non-stop to get the event 7 (RCR-). What is wrong in the process? Some suggestions? Thank you. Best regards Zheng wu