Thanks for the query.
Have you enabled SNMP on virtual machines (guests) and the community name provided in OME's discovery range configuration is also correct?
Thanks for the information.
Virtual machine SNMP setup looks perfect. Could you also check for SNMP and WSMAN protocol tests against the ESXi host? Success of both is required on the host.
Please note: This detailed white paper is always handy while managing virtualization environment with OME - http://en.community.dell.com/techcenter/extras/m/white_papers/20424220