This problem is getting frustrating. When I get a partial fill on ARCA, I get thrown to the back of the order priority at my price level. Today, I got a 53 share partial fill and the balance of my 800 share sell order was put in the back of the order queue. It happened yesterday and other previous days also. This same problem used to occur with Island orders, but IB fixed that a long time ago. I wish that they would put the same fix into their ARCA interface software. I think that they are cancelling and resubmitting the order when they get a partial fill. This creates another problem. Orders with less than 100 shares remaining are cancelled. This includes position closing orders. Are others frustrated with these problems? Any chance of a fix by IB?