Have you moved the distributor at all?
Is it almost starting with a backfire?
If you have fuel and spark at the plugs and if the firing order is correct the only other reasons it wont start is timing or compression. Since you have been playing with the dizzy im guessing its timing but you shouldnt mess it up replacing a cap and button. Im thinking along the same lines as BRUTE, is most likely something very simple. Tripple check firing order and make sure you know which is No1 on the cap. Make sure cap is fitted correctly and look really hard for a wire you may knocked of the coil or the side of the dizzy.
God luck