power problem

i have an lcd hooked up to my arduino uno, it is using the 5v on the arduino, i am trying to hook up a button and i need to use the 3.3v on the arduino, but whenever i put the other ground that i need for the button in, the lcd stops working. i could take out the 3.3v pin and the ground pin would still make the lcd stop working. if i put ether one of them on an external power source they don't work. any solutions.

the image wont upload correctly but here is the diagram url:

Read How to use this forum, and post your sketch (code), schematic in CAD or a picture of a hand drawn circuit in jpg or png- (please, not a pretty Fritzing drawing)

We can't possibly guess how you have things wired.