Simplest shift register test circuit - clock
the problem you have is probably contact bounce

here's a simple de-bounce circuit, it uses no semiconductors, but it reqires a SPDT switch, 







simulate this circuit &ndash; Schematic created using CircuitLab

Another possible problem is ground bounce, be sure to have a capacitor of at-least 100nF connected directly across the power pins of the chip, especially if you're using solderless breadboard.