Your program could be written better. If the second IF block in the main loop() never executes then your sensor never updates after the first time. Likewise, if the execution stays in the second IF block your sensor will also not update after the first time.
But your problem is likely that your variable lastStreamTime is never updated at all. You set it to zero at the beginning and that's it. Your program probably stays in the second IF block forever.
A simple print statement between your two IF blocks would have clued you in to this.