Welcome to the forum.
SONAR 4 is old and probably does not have native VST support, which is why you need the VST adapter. And that may not work on a 64-bit machine.
I see that you are doing voice-overs but it still may be a good investment to purchase a newer recording software, like Cakewalk's Music Creator 6 or MC 6 Touch (about 49 USD), or even SONAR X3 so modern VST instruments and effects can be used.