What did lamarck think evolution involved that caused his ideas to be incorret?

Lamarck believed that traits acquired by one individual, will be immediately passed down on it's descendants. FE: If your father was a smith, you will have stronger muscles and bigger hands. Which is not true because evolution like that happens over thousands maybe millions of years and genetic changes are only expressed if the mutations occur in the DNA of the reproductivecells (spermproducingcells etc)

Note: Lamarck has proven to be right by scientist nowadays in the point of genetic expression: Children of people who survived the Hunger Winter in Holland of 1944 have more chance on heart diseases and become thicker more easily. This change is directed to the fact that certain events can activate certain genes, thus stating that Lamarck's theory isn't entirely wrong