What a rejection means
A rejected order is one the broker refused to accept. Nothing opens, nothing changes, and you are back where you started. The key is finding the specific reason, which the platform usually records even if the pop-up was vague.
The common reasons
Not enough free margin for the size. An invalid stop-loss or take-profit (too close, or wrong side). An invalid lot size. The market closed for that symbol. Trading disabled on the account or symbol. A price that moved ('off quotes' or a declined requote). Or a connection drop at the wrong moment.
How to diagnose it
Read the Journal tab — it logs the reason for each failed order. Match what you see there against the list above. Then test the smallest possible change: reduce size, widen the stop, or pick a clearly open symbol, and see which fix lets the order through.
How to prevent it
Size within your free margin, respect the stops level and volume step, trade during open sessions, and keep a stable connection. Most rejections disappear once these basics are habitual.
Broker's fault or yours?
The overwhelming majority of rejections are on your side and easily fixed. Genuine broker-side problems — trading disabled without reason, or refusal to let you close a position — are the exception and deserve a written complaint and a hard look at whether to stay.