Passing Byte arrays to a function...?

[Wokawidget]

Ok, I know a funtion can return a byte array:

Private Function Woof() As Byte()
   'Blah Blah
End Function

Now why can't I do this:

Private Function Woof(ByVal Buffer() As Byte) As Byte()
   'Blah Blah
End Function

But...ByRef works!!! Hmmmmmmmmm...any ideas?

Woka