Преобразование массива через процедуру - VB

Private Sub Command1_Click()
Dim arr(1 To 20) As Single, max As Single, maxI As Integer
Dim min As Single, minI As Integer
txt = ""
For i = 1 To 20
    arr(i) = Int(100 * Rnd - 50)
    txt = txt & arr(i) & " "
Next i
txt = txt & Chr(13)
max = arr(1): maxI = 1
min = arr(1): minI = 1
For i = 2 To 20
    If arr(i) > max Then max = arr(i): maxI = i
    If arr(i) < min Then min = arr(i): minI = i
Next i
If Abs(maxI - minI) > 1 Then
    If maxI < minI Then Call nul(arr(), maxI, minI) Else Call nul(arr(), minI, maxI)
End If
For i = 1 To 20
    txt = txt & arr(i) & " "
Next i
    MsgBox txt
End Sub
Sub nul(ByRef a, M, N)
For i = M + 1 To N - 1
    a(i) = 0
Next i
End Sub