There is a system that rejects the trade if there has been a certain deviation from the market price at the time of the execution. I am uncertain it was targeting you specifically, just how the system works. If you see the price is 1.2780 and after executing the trade you discover you entered at 1.2775, when you intended to place a put option, would you be satisfied? If you were doing very well, these rejects might be a polite way of asking you to leave. Another option is that too many traders were already holding a trade in the direction you wanted to place and the system blocked you maintain a healthy book balancing, another possibility. The big kick is when you actually try to exit the trade before the expiration, that's when you're usually flooded with re-quotes. Anyone experienced it?