I have changed all the modification you people suggested but am stil not resolver this code from bug.
public long GetPOCVolume() => ladder.Max(kv => kv.Value);
public long GetPOCVolume(TradeSide side) => ladderBidAsk[ (int)side].Max(kv => kv.Value);
public long Volume() Volume => ladder.Sum(kv => kv.Value);
public bool IsEmpty() => ladder.Count == 0;

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