informix with NIS

We recently converted a HP 9000 series 800 machine running hp-ux 9.04 to an NIS client, rather than get passwords from /etc/passwd. The machine also runs an informix server (v7.11). The problem is that users (clients) can no longer connect, when they run their programs (*.4ge). They get an error, which says that they are not known by the database server, although they can login to the server. Here is a typical error message: 17:29:16 listener-thread: err = -951: User xxx is not known on the database server. However, when i remove the user from NIS and put them back on /etc/passwd on the informix server, everything works. So what am i looking at ... something buggy with NIS on hpux9.04 or doesn't informix know how to look at NIS? (users are included through NIS using netgroups) any ideas? (btw i am not much of a database person). thx -rr