Closing positions at a higher gain than in receiving

Can someone please help me with this, I’m paper trading futures with $1000 as practice for when I save up the money to actually trade them. I’ve noticed when I close positions that the gain shown in trading view is not accurate, for example I have +$102.00 on the graph, and when I sell it within the same 5 seconds it fills at +$70.00, and on occasion I close in a profit and it fills as a loss.