Why the Schlieffen Plan failed

I feel like Germany should have thought through their plan better, it seems like they were so excited when war was declared that they just needed to immediately carry it out. They should have thought about the fact that their army was huge and it was going to be hard to feed and move. I think it was a good plan, I'm definitely not saying that it was a bad plan because I think it was pretty ingenious for them to think of encircling their enemy in an unsuspecting way, but it wasn't thought through to the length that it should have been. They should have had a steady food supply, and a way to transport it to them already planned out.  Also it should have been considered that the army was going to get tired after a few weeks and not be as productive, thus not being able to carry out the plan as well as they thought. Thus overall I think it was a good plan i just don't think every detail was thought through thus it caused its failure.