There was nothing "wrong with them". They weren't ready for a Blitzkrieg man! You have to remember that France sustained massive losses in ww1, which they were still recovering and shocked from. They really didn't want another war, but more or less had to defend themselves. One major thing was that France wasn't prepared or expecting such a full-forced Armored/mobile assault, especially as fast as the Germans moved. They built fortifications/etc and were basically preparing Infantry defenses in fixed locations, readying themselves for a long, drawn-out battle. The breaking/flanking of the Maginot Line and the push through the Ardennes by the Germans in 1940 were the downfall of France.

TLDR: They simply weren't ready for a Blitzkrieg/Full-on Armored and Mobile Assault