Multiple Instances Problem

I have 2 Online-Instances running under SINIX-Y V5.42 on a RM600. Informix Version 6.00.UE1. Let's say one is named server01 with the alias server01_net for net access, the other server02 with the alias server02_net as well. server01 emphasizes net access, so the tlitcp is set to CPU and ipcshm to NET-VP, while server02 emphasizes local access. If i set the INFORMIXSERVER-variable to server01 and the ONCONFIG-variable to the appropriate value and add a dbspace using onmonitor, it is added to server02! Also, if i try to dbimport in this situation i get an error message that says, the Servername could not be found in neither DBSERVERNAME nor in DBSERVERALIASES?. The solution i found, was to set the INFORMIXSERVER-variable to the net-alias of server01 -> server01_net. But i cannot seem to use it's real name server01. I can't understand that this should be normal behaviour. Please give me your ideas on this subject. Sincerely, Roland