I am trying to lock a signature and it a warning popped up saying "All required fields must be filled out prior to lock" and all the fields have been completed. What do I do?

If all the signature  fields are completed then check your call times.  Make sure your times are correct and applicable to your call.  

In the example above the dates are a day ahead which day ahead which is causing the issue.   Once the dates are corrected you will be able to lock the signature.