First make sure you have the latest firmware version 2.0.0.29 and bootcode 1.0.1.01 and try again.  If this doesn't work, try querying the Q-BRIDGE-MIB to display the forwarding tables on vlans.  This mib is vlan aware whereas the newer mib may not be.   
I am trying to read a Power Edge 3448 switch's forwarding table through snmp.  Usually one does this by walking the table at  .1.3.6.1.2.1.17.4.3.  However this switch has VLANs, and I am presuming that the suspiciously spare table I am able to read means that this switch is maintaining a separate table for each VLAN. If this was a cisco, I would tell the switch which VLAN I want to read by appending it to the end of the community, like this: snmpwalk -v 1 -c 'public[NAME]' $IP .1.3.6.1.2.1.17.4.3 ...would return the forwarding table for VID 130.   However, my 3448 doesn't seem to like this notation. Can anyone tell me what the correct notation is, or point me at a web page where it is documented? Thank you for your time.
How do I specify VLAN in SNMP community?