Opening a single position for critera

Hi,

I am rather new to codeing cbots with my experience limited to VBA and MathLab in the past.

During backtesting, I noticed in my trade history multiple trades opening on the same time period when critera is met, skewing my results.

I would like only 1 trade to be placed when the critera is met.

My setup is:

if (Criteria1 && Positions.Count == 0 && Criteria2)
            {
                PlaceLimitOrder(TradeType.Buy, Symbol, VolumeInUnits, Limit, label, SL, boll2.TP);
            }
            else if (Criteria1 && Positions.Count == 0 && Criteria2)
            {
                PlaceLimitOrder(TradeType.Sell, Symbol, VolumeInUnits, Limit, label, SL, TP);
            }

Criteria1 and Criteria2 are based on movement in bollingerbands.
The if statement is run in the OnTick() instance.

besides Positions.Count I have also tried

longPosition == null

with

             longPosition = Positions.Find(label, Symbol, TradeType.Buy);

Any advise would be much appreciated.