How to accumulate total in one cell from another if input changes

Hi,

I am trying to create a roulette excel game.

I have a cell with how much I want to bet and if I win then money is added to a cell, if I lose money is taken away.

So basically I have cell B8 which is where I enter how much money total I want use during the game, but not bet total, there will be other cells where I enter how much of that total I want to bet.

I then have a cell C8 which shows how much I won and adds that to cell D8. This cell D8 is what I want to accumulate. Im guessing I need a macro of some sorts.

I have use the below macro:

Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Address = ["D8"] Then
[D8] = [C8] + [B8]

End If
End Sub

This works if I manually put a value in C8 but if I put a formula it does not work:

=B8 + IF(ISBLANK(C8),0,IF(E11=C3,C11*36,0))

when E11=C3 it shows in cell C8 but does not accumulate.

Any advice?

Thanks