Afaik, TimeSynchronizer needs timestamps to match exactly. If you don't have that happening in your message stream, but still want callbacks for messages that are "close enough", then you should perhaps be using the ApproximateTimePolicy.
Summarising: TimeSynchronizer needs timestamps to match exactly. If you don't have that happening in your message stream, but still want callbacks for messages that are "close enough", then you should perhaps be using use the ApproximateTimePolicy.