Range Variables In Customized Function

I wrote my function as it is shown below:

Function MyFunction1(r, n, xrange, yrange)
If r <= n Then
For i = 1 To 5
MyFunction1 = MyFunction1 + xrange(i)
Next
Else
For i = 1 To 5
MyFunction1 = MyFunction1 + xrange(i) * yrange(i)
Next
End If
End Function

This is just a very basic idea of what I need to do, so it might not make sense why I am doing it, but I am just trying to test that the function works. Anyhow, the thing is that it works with something like this when I input it in a cell in a worksheet: =MyFunction1(RAND(),0.5,{5,6,7,8,9},{10,20,40,50,100})

However, if I try to define the range or set {5,6,7,8,9} with other cells, it does not work. so for example if I try the following:............