Paddy...replace your code with this below
Run it.
Click on your command1 button
What number appears in the msgbox when it runs?

Code:
Option Explicit

Dim oExcel As Excel.Application
Dim wkobj As Excel.Worksheet
Dim wkbobj As Excel.Workbook

Private Sub Command1_Click()
List1.Clear
Set wkbobj = GetObject("F:\Machine info for HQ and FQ Shrink Tunnel.xlsx") 
Dim i As Integer, numrows As Integer
numrows = wkbobj.Worksheets(1).Range("A1").CurrentRegion.Rows.Count

MsgBox numrows

For i = 1 To numrows
    List1.AddItem (wkbobj.Worksheets(1).Range("A" & i).Value) 'where "A" is the column you want loaded
Next i
End Sub

Private Sub Command2_Click()
List1.Clear
List1.AddItem ("Good by")
List1.AddItem ("Adios")
End Sub