AIX uses several configuration files to screen its communications. One of the file, snmpd.conf, needs to be changed so that the SNMP daemon accepts the incoming messages from the SMUX subagent. For more information, see the online manual page for snmpd.conf. You need to add a line to define each subagent.
For example, you might add this line to the snmpd.conf:
smux 126.96.36.199.188.8.131.520.1 ““ IP_address net_mask
IP_address is the IP address of the host the subagent is running on, and net_mask is the network mask of that host.
Do not use the loopback address 127.0.0.1, use the real IP address instead.