From Net-SNMP Wiki

Why can't I see anything from the agent?

There are two main general causes of problems retrieving information from the agent. Either the client tool may not like the request (and refuse to send it at all), or the agent may not respond with anything useful. The simplest way to distinguish between the two is to run the command with the command-line option '-d'.

If this doesn't display a hex dump of the raw outgoing packet, then it's the client side which is dropping the request. Hopefully you should see some form of error message, to help identify what's wrong.

If this displays one or more outgoing dumps (but nothing coming back), then the request is failing at the agent end. See the next entry for more details.

If you see dumps of both the outgoing request, and a response, but no results are displayed, then either there may be a problem with decoding the response (in which case you should see an error message), or the agent may simply not support the requested information (and the response is being discarded as irrelevant).

   FAQ:Applications
   

1. How do I add a MIB?
2. How do I add a MIB to the tools?
3. Why can't I see anything from the agent?
4. Why doesn't the agent respond?
5. I can see the system group, but nothing else. Why?
6. Why can't I see values in the <ENTERPRISE> tree?
7. The agent worked for a while, then stopped responding. Why?
8. Requesting an object fails with "Unknown Object Identifier" Why?
9. Why do I get "noSuchName" when asking for "sysUpTime" (or similar)?
10. Why do I sometimes get "End of MIB" when walking a tree, and sometimes not?
11. How do I use SNMPv3?
12. Why can't I set any variables in the MIB?
13. Variables seem to disappear when I try to set them. Why?
14. Why can't I change sysLocation (or sysContact)?
15. I get an error when trying to set a negative value - why?
16. I get an error when trying to get a string-indexed table value - why?
17. What quotes should I use for string index values?
18. How do I send traps and notifications?
19. How do I handle traps and notifications?
20. My traphandler script doesn't work when run like this - why not?
21. How big can an SNMP request (or reply) be?
22. How can I monitor my systems (disk, memory, etc)?
23. Applications complain about entries in your example 'snmp.conf' file. Why?
24. OK, what should I put in snmp.conf?
25. How do I specify IPv6 addresses in tools command line arguments?