Is it your first trade?
If not, have you made losses while trading in the same account before?
It is not my first trade and I made losses on trades before, but this should not effect my current position i think

I closed the possition now (but I missed to make a screenshot) and even when my realised profits where negative I made some profits because my unrealised profits was higher then my realised profits. It is still confusing because I dont now how to calculate it correctly.
Can I calculate my unrealised profits minus my realised profits to see how much the profit will be? How do you calculate it?
And why the realised profits turn in positive profits sometimes?
I read about it on Bitmex but its still confusing, I thing there should be a easy understandable way to figure that out

Thank you for your answers!

The site is trying to tell you that prior to this, you've lost money on trades. The amount you've lost on all prior trades is -0.0004 BTC. The amount that you've made on this one particular trade is .0086 BTC, and you haven't realized this profit yet. The way to realize this profit will be to close out your trade.
Once that happens, your realized profit will change to .0086-.0004 = Realized Profits.
I'd recommend not using BitMex too often, doesn't usually end well.