I can't add/record iMovie voiceovers

Basically what happens is that every time I click the voice over icon to record it has the little ding noise and it just won't work. I feel like this is an issue with the events or I have too much storage filled up but even if I delete things it still won't record, but if it is something to do with my events being full I don't know how to make it automatically save on a different event every time I record something.