VBA Function to fill empty cells with last non empty value

I'm trying to develop a simple code to fill empty cells with the last non empty cell as shown in the image:

Function FILL(x, y)

If Not IsEmpty(y) Then

FILL = y

Else

FILL = ActiveSheet.ActiveCell.Column.End(xlUp).Select.Value

End If

End Function

The code above return #VALUE! on the empty cells instead.