ER problem HPUX - Linux

We are using Informix ER to replicate about 40 tables tween two different Informix Servers. The 'Publisher' runs the database on a HPUX server with version 7.31 of informix and the 'receiver' runs the databases on a Linux server with also version 7.31 of Informix. Things seemed to work fine for a few days, but after that period replication suddenly seemed to be stopped. I checked the status of the replication with command 'crd list repl' on the reciever and i got to see a list of all the replications and they all had the status Active. The statement 'cdr list server' shows that both replication servers are active. After stopping the replication process and restarting it things seem to be working well again. I have no records in the ATS amd RIS directories. Does anyone have any idea what might be the problem? Now i am not sure how long things will work correct and the 'cdr list repl' command seems to display me the incorrect status when replication stops. Sjaak van Esdonk