A man every day goes to office - With Answer

A man every day goes to office 2 hours late and comes after 2 hours. He goes to office by lift upto 9th floor and more 3 floors goes by walking but while returning he comes by lift from 12 th floor, why?

Man and the lift puzzle - Can you Answer ? 

See Answer below:

Answer: The person is not tall enough to reach the button for 12th floor in the lift, but while returning he can press 0 to reach ground floor.