Idk if im dumb or smthn

I started as germany in 1936

started building army made most of divisions with 12 infantry batalions,2 artilery batalions,engeneer artilery and anti-air support company

Started war on poland and crushed it within month

Invaded benelux with some complications

Completly stopped on france

What am i doing wrong?my theory is that i havent enought tanks but im not sure