Understanding trade detector shown information

[Photon66]

In the below figure, a volumetric bar with trade detector indicator is shown. The trade indicator creates the circle in the middle. I have difficulty understanding the trade indicator info. In the highlighted section from indicator, it indicates "S:2" whereas the volumetric indicator shows 0 sell. What does it mean? I would appreciate if someone could explain the discrepancy. Thank you.

[NinjaTrader_ChelseaB]

Hello Photon66,

This means volume of 2 on the sell side.

Below is a link to the help guide that explains what this means.

https://ninjatrader.com/support/helpGuides/nt8/index.html?order_flow_trade_detector.htm#OrderFlowTradeDetectorOverview

[Photon66]

Thanks for the reply. I guess I have difficult understanding the difference between the Last volume, Bid volume, and Ask volume.
Should not this be true? Last volume = Bid volume + Ask volume.

At one moment in time I get these values for volumes of Ask, Bid, and Last as shown below. Here the Bid and Ask values are huge compared to the last. Why is there such a huge difference? Thank you.

[NinjaTrader_ChelseaB]

Hello Photon66,

Ask are buy orders.
Bid are sell orders.
Last is the last transaction which happens at either the bid or the ask.

It is not the volume of both.

There are more orders on the ask and bid working, that the last transactions.