Quantity need must be equal or lower than 0 while trying to buy stocks

First thing first. Why my post being flagged? I know I can send official mail to you guys. But unfortunatelly it takes times. I send two already, and I didnt get anserws on any of them.
So I would like to as you and community.

What does it mean “Quantity need must be equal or lower than 0” when I am trying to bius stock, it doesnt make sens right?
Or does it?


Hello, Suule.
It is a question which has popped up frequently, you can find an answer here: