If its recognized as SNMP it won't pull the config as its not a known device to RME (thinks its not supported)
Can you try deleting this device from the inventory and then adding it, however, this time only give the RO and RW comm strings as credentials. If it is successful then go ahead and edit the attributes and add telnet user/passwords
If it fails you might want to look at turning on some inventory debugs: (look at commands to enable DIServer debugs)
http://www.cisco.com/warp/public/477/RME/rme_inventory_faq.shtml#Q8
then debugs will be in the daemons.log on Solaris, DIServer.log windows