How To Output 1x10 Array

trying to output a 1x10 array of the function FwdRate. The inputs are all 1x10 horizontal ranges of numbers. So for example to calculate FwdRate 1 I need to take the first values from each of the input ranges and enter them into the formula below ! Where am I going wrong as all I get is the VALUE error when I press ctrl+shift+enter ?

Option Explicit
Function FwdRate(Tau As Range, f1 As Range, dtau As Range, vol1 As Range, vol2 As Range, vol3 As Range, m As Range) As Variant
Dim VArray() As Double
Dim i As Integer
Dim n As Integer
Dim dt As Double
Dim X1, X2, X3 As Double

[code].....