hi...
for IPM to work router IOS should support SAA (service assurance agent) so please make sure whether your router IOS has this feature;(SAA support)
and check whether the router you are trying to add as a source collector is already managed by RME,if not add that router to RME,then try IPM
and please make sure your snmp community strings are properly configured and check anything is blocking SNMP traffic between server and routers..
rgds..
Shiju V.Joseph
Automation Experts