Private Sub UserForm_Initialize()
Dim myPrefixes() As String
Dim strPrefix As String
Dim i As Integer
    myPrefixes = Split("[Select Item]|Mr.|Ms.|Det.|Dr.|Atty.|Rabbi|Ofc.|Sgt.|Cpl.|Maj.", "|")
    With Prefix1
        .List = myPrefixes
        On Error Resume Next 'the variable is missing from the document
        For i = 0 To .ListCount - 1
            If RTrim(ActiveDocument.Variables("Prefix")) = .List(i) Then
                .ListIndex = i
                Exit For
            End If
        Next i
    End With
End Sub

Private Sub CommandButton1_Click()
    If Prefix1.ListIndex <= 0 Then
        MsgBox "Select the prefix"
        Prefix1.SetFocus
        Exit Sub
    End If
    ActiveDocument.Variables("Prefix") = Prefix1.value & Chr(32)
    Unload Me
End Sub