writing a function

[lior03]

hello
the aim of the following procedure is to allow the user not to add an input but still to get a result.if he omit the width input the function use the lengh input to return
[VBA]
Function addtroble(length As Long, Optional width As Long) As Long
Application.Volatile
If IsMissing(width) = True Then
addtroble = length ^ 2
Else
addtroble = length * width
End If
End Function

[/VBA]
why do i get a zero as an answer.?

[Bob Phillips]

[vba]

Function addtroble(length As Long, Optional width As Variant) As Long
Application.Volatile
If IsMissing(width) = True Then
addtroble = length ^ 2
Else
addtroble = length * width
End If
End Function
[/vba]