Can somee one tell me how to populate a combobox from a Defined List named Surname on worksheet called EmployeeDetails on a worksheet in a separate workbook named Defined Names List.xls

I have tried to enter the following in the Userform Combobox Properties Row Source

['Defined Name List.xls]EmployeeDetails'!$b$2:$b$50 but it doesn't like it

This is the Combobox code

Private Sub cboSurname_Click()
Dim Rw As Long
With Worksheets("EmployeeDetails")
Rw = .Range("B2:B50").Find(Me.cboSurname.Value, LookIn:=xlValues, _
lookat:=xlWhole, MatchCase:=False).Row
Me.txtFirstName.Text = .Range("A" & Rw).Value
Me.txtHourlyRate.Text = Format(.Range("c" & Rw).Value, "$#,##0.00")
End With
End Sub


Can someone point me in the right direction