OK. Here is what you need. First, dot1dTpFdbAddress is part of the bridge MIB (BRIDGE-MIB (RFC1493)). I suggest you look at SNMP::Info::Bridge and use it. If you want to do it "by hand" as you did before, the OID is

.1.3.6.1.2.1.17.4.3.1.1

HTH, --traveler