Was the German Defeat on the Western Front Caused by the Failure of the Schlieffen Plan?

After German foreign policy had caused the country to have hostile countries on either side - France and Russia - Germany needed a plan to win a war on two fronts. This plan was devised in the early twentieth century by Count Alfred von Schlieffen and then tinkered with fairly extensively by the younger Moltke right up until 1914. It is known as the Schlieffen Plan.
The plan's idea was to have a lightning invasion of France through the Low Countries while keeping light defensive forces on the Eastern Front with Russia, and when France was knocked out to turn the army to the East.…