The Maginot Line performed magnificently for what it was designed for: prevent German troops from moving any significant invasion force through the space covered by the Maginot Line. The French could see that that line didn't extend for the entire length of Germany's western border. Also, the French command had fought though World War I and therefore knew perfectly well that the Germans already had, and therefore could, come around the north. They had further plans to use the bulk of their troops to meet that further north.
This is discussed in several postings in the FAQ section Maginot Line and Fall of France. NOTE: mentioning previous answers is not intended to discourage further or followon questions or debate.