The price can change from the time you place your order to when it arrives at the broker. This is especially likely if you are an active trader chasing news or

The price can change from the time you place your order to when it arrives at the broker. This is especially likely if you are an active trader chasing news or momentum where others are likely trying to buy at the same time. It's like aiming a rocket, or in your case, an old Honda Civic, at a fading star. Have you looked at what the book state was after you placed your order in the cases where you don't fill? If you have a working order priced through the market that's unfilled, take a screenshot and name & shame your broker here.