having a lil prob... may be normal

I just installed cans on my 95 accord. and i drove it around and locked the back all the way up and it bounced like crazy lol. So i tapped the down switch for the back, the bouncing quit but then this knocking noise started i drove real slow and like... every few feet it would pop... but when i tap that switch again it rides fine... whats the problem... anyone know??