Why can't use libsnmpv3.a?

I want to set the trap version to version 2. So I should compile the project with the library libsnmpv3.a. It can compile. But the SNMP daemon can’t work well. I can only browser the MIB node once, then the SNMP daemon is dead. And the browser can’t get any responses from the unit. What is the reason? Does anyone have this question? thanks