Home button ribbon doesn't fit.

Make sure that you are buying the home button for the correct model. Different iPads use different parts, and if you accidentally ordered the wrong part, it is not likely that it will work. There is not a one size fits all replacement for every model iPad, and each model of iPad is quite similar. The easiest way to identify your iPad is by the model number, there is a tool on the apple website to do this, and once you do that, match the models on the iFixit website and order from there.