Hi--Here's some things to check:
Look at RME> Administration> Inventory> Import Status
are any of the devices in question listed under "Device Attribute Errors"?
Any ACLs on the device?
Are your SNMP community strings, userid/password correctly configured in CW2K and the device(s)?
If you can't narrow it down with the above, please post the following:
RME version and current IDU loaded (should be 9).
Type of device(s) failing?
hth