Hit 956 error when bring up informix Online Dynamic Server

Hello, When I startup informix online dynamic server (version 7.12.UC1), it always give warning message saying Network deamon is down. I get these messages in the online.log: : 19:09:42 Dataskip is now OFF for all dbspaces 19:09:42 Quiescent Mode 19:09:42 Checkpoint Completed: duration was 0 seconds. 19:10:03 listener-thread: err = -956: Client host or user (informix@singsun2.sing.cig.mot.com) is not trusted by the server. 19:10:06 listener-thread: err = -956: Client host or user (informix@singsun2.sing.cig.mot.com) is not trusted by the server. Anybody has encountered this before? Please response to qsg0034@sing.cig.mot.com if you know the solution. Thanks. Regards, Lai