It happens, to everybody.
It's not the end of the world. It is a learning opportunity.
It's not always the crowd's fault. BUT they can play a part.
It doesn't matter if it was a small crowd. Personal funny stuff goes over even in very intimate surroundings. Don't tune your timing and mind to big laughs, just laughs, that's all you seek.
*Booming laughs from a big crowd is just small individual groups of people laughing all at once. ;)
Too many bad sets in a row is a red flag that signals back to the drawing board.