Previously check first, do you use sell orders or not, if the case is as you tell, I think you used sell orders beforehand
Thats true and very nice advise, but sometimes even we double check it traders experience bad luck because they can't expect the traps due to volality fluctuations.
Maybe OP already set sell order after his buy order executed and think if sell in 49 is already make profit. Usually we don't know in where price of coin that we bought will fly. And then we sell it lower price and it keep increased.