Hello, I am clicking on Add Indicator on a chart, than I click on Write Indicator Formula, than I copy paste your code and it says Formula Error in red?? Why isnt this working?

This is the formula I am copying/pasting:

Static Sum As Single
Static SumSq As Single
Static BB As Single
Static Keltner As Single
If isFirstBar Then
    Sum = 0
    SumSq = 0
    Keltner = 0
Else
    Sum += Price.Last
    SumSq += Price.Last^2
    Keltner += 1.5*(System.Math.Max(Price.High,Price.Last(1)) - _
        System.Math.Min(Price.Low,Price.Last(1)))/20
    If CurrentIndex >= 21 Then
        Sum -= Price.Last(20)
        SumSq -= Price.Last(20)^2
        Keltner -= 1.5*(System.Math.Max(Price.High(20),Price.Last(21)) - _
            System.Math.Min(Price.Low(20),Price.Last(21)))/20
    End If
End If
If CurrentIndex >= 20 Then
    BB = 2*((SumSq - Sum^2/20)/20)^.5
    Plot = BB/Keltner
Else
    Plot = Single.NaN
End If