Insufficient Margin - order cancelled !


Hi @Dargo,


Today  at 12:25:30 CET 14.12.2015, At the moment when someone did a market sell of ca. 300 or more coins
price went down in a matter of seconds from 406-->397.19

https://i.imgur.com/1sOfeNr.png


https://i.imgur.com/O3F4gUU.png

As you can see, a few minutes earlier, at 12:14:22 CET, I had successfully opened a small margin LONG order (5x lev  11BTC-long). Surprisingly, this order was cancelled by the system at the very moment [12:25:36] when it should have been executed.
Reason: Insufficient Margin


Why is that?
-I had sufficient coins available.
-Usable margin balance must have been sufficiente, because I had no other position open at this time.

Thanks for taking the time to explain.