Specifying The Range To Show In The Popup

I am coding a right-click popup and need some help specifying the range to show in the popup. The code is listed below.

How I can I adjust this code to show the range O400:O440 only? Right now it shows the entire column from O400 down.

Private Sub Worksheet_BeforeRightClick(ByVal _
Target As Range, Cancel As Boolean)
Dim objBar As CommandBar
Dim objButton As CommandBarButton
Dim introw As Integer
introw = 400

Cancel = True
On Error Resume Next
Application.CommandBars("avail").Delete
On Error GoTo 0
Set objBar = Application.CommandBars.Add("avail", msoBarPopup)
Do Until IsEmpty(Cells(introw, 15))
Set objButton = objBar.Controls.Add
With objButton
.Caption = Cells(introw, 15).Value
End With
introw = introw + 1
Loop
objBar.ShowPopup
End Sub