How does IB TWS calculate P&L

i find that when i scale in and out the IB calculation of Unrealized and Realised PnL is incorrect.
As you can see in the morning, i only had 1 loseing trade which was the first one. I should have had a -77.6$ loss, however it shows -117$

I already opened a ticket on it but IB responds very late and by that time, my positions have changed.

Does any one know or come accross this issue

The picture contains your live account number. May I suggest that you take down the picture or edit your account # out of the picture for your own security? I realize the security device might negate what I wrote somewhat but still.

I think the P&L is reported based on midpoint bid/ask, not on actual bid/ask. Not sure about scaling in / out and #s changing in your case. What do you mean by "scale in"?

Thank you FXEz,
If you look at the trades
the first 2 executions resulted in a loss

The other executions were profitable and i have been in middle of a trade with open position. So the only Realized PnL is based on the first 2 executions.

Realized PnL is based on actual net gains at time of trade. once a trade is closed, the Realzied PnL number cannot change based on price as its done deal in past.

I am still trying to figure out why there is this discrepency.
IB has not responded yet.

I did some calculations and put them in an Excel sheet. I might be off in my calculations. Maybe it will give you some ideas?

I think they calculate pnl by average position.

Thank you so much for your effort. This might be the closest explanation that i got so far. Makes me wonder how to monitor my open pnl going forward.
I probably need to write a program to monitor for the correct details.
My target is 20 pips a day and i did not pay close attention to this before.