Dynamic Combobox

Hi

I would greatly appreciate some appreciate some help from the experts in this forum, please help if you can.
I am trying to make the listing range for a combobox dynamic. The combobox listing ranges change depending on the value of a cell.
i have 3 listing ranges for one combobox, the ranges are factory1, factory2, factory3, all these ranges are static and i would like to make them dynamic.
i have attached an example file. below is the code i am using:
[Sub MAIN()
Dim PT As Range
Dim i As Long
With ActiveSheet
setNames .Range("a6")
Set PT = .Range("b1")
i = 1
Do Until PT = ""
If .Range("a1").Value = PT.Value Then
On Error Resume Next
.ComboBox1.ListFillRange = ThisWorkbook.Names("factory" & i).RefersToRange.Address
If Err.Number = 1004 Then
MsgBox "not defined name: factory" & i
ElseIf Err.Number <> 0 Then
MsgBox "unexpected error: " & Err.Description
End If
On Error GoTo 0
End If
i = i + 1
Set PT = PT.Offset(0, 1)
Loop
End With
End Sub

Sub setNames(theTopLeft As Range)
Dim theName As Name
Dim nameStr As String
Dim theRng As Range
Dim i As Long
Application.DisplayAlerts = False
theTopLeft.CurrentRegion.CreateNames Top:=True, Left:=False, _
Bottom:=False, Right:=False
Application.DisplayAlerts = True
For Each theName In ThisWorkbook.Names
With theName.RefersToRange
For i = .Cells.Count To 1 Step -1
If .Cells(i) <> "" Then Exit For
Next
End With
If i <> 0 Then theName.RefersTo = theName.RefersToRange.Resize(i, 1)
Next
End Sub][/CODE]