I faced same problem. I tried to run example "Writing a Dynamically Loadable Object" at Windows 10 x64. Version Net-snmp 5.9.4. Compiler MSVC 2019. Net-snmp build without problem. I build agent plugin DLL in Qt Creator. When i try snmpget localhost NET-SNMP-TUTORIAL-MIB::nstAgentPluginObject.0 i get only "No Such Object available". When i try to debug this situation, i discovered that my init_nstAgentPluginObject called by SNMPD - register_mib return SUCCESS, but i can't find my MIB in agent OID...