VBA treeview loading issue - invalid key

Question

I want to display the Excel data in treeview but it is showing invalid key. Please assist me.

Dim rTWData As Range
Dim oRow As Variant
Dim onode As Variant
Dim lastrow As Integer

Dim myFileNameDir2 As String
Dim ws12 As Worksheet
Dim i2 As Integer
Dim lastrow2 As Integer
Dim filecheck As Variant

myFileNameDir2 = Sheet1.Range("V5").Value
Workbooks.Open Filename:=myFileNameDir2, UpdateLinks:=0
Set ws12 = Worksheets(1)
lastrow = ws12.Range("A" & Rows.Count).End(xlUp).Row - 1
Set rTWData = ws12.Range("A2:L" & lastrow)
With TreeView1
    Set onode = .Nodes.Add(, , "root", "+")
    onode.Expanded = True
    For Each oRow In rTWData.Rows
        .Nodes.Add "root", tvwChild, oRow.Cells(1, 1).Value, oRow.Cells(1, 1).Value
        .Nodes.Add oRow.Cells(1, 1).Value, tvwChild, oRow.Cells(1, 2).Value, oRow.Cells(1, 2).Value
        .Nodes.Add oRow.Cells(1, 2).Value, tvwChild, oRow.Cells(1, 3).Value, oRow.Cells(1, 3).Value
        .Nodes.Add oRow.Cells(1, 3).Value, tvwChild, oRow.Cells(1, 4).Value, oRow.Cells(1, 4).Value
    Next
End With

Answer 1

One of the oRow.Cells is empty or is a number.

The key must be a string (must contain a non-numeric character).