In the documentation I can read that Buy-Orders are opened with the Ask price and
Sell-Orders are opened with the Bid-price.
When you close the order you must take the oposite.
In my demo account I can start and close orders with Ask and Bid price.
I can mix it. It functioned - I get no error message.
Do I get problems when changing to a real money account ?
When you close an order, you may get on better using OrderClosePrice() rather than Bid or Ask.