Runtime Erro "9" Subscript out of range - vba

Question

so this code was made in excel 2013 and the workstations I have to use it on operate with 2003. In 2013 it works just fine, when it's in 2003 it returns "Runtime error "9" Subscript out of range". If someone could help me figure this out I would appreciate it. It appears the issue is with this bit of data
Set wsSheet = Worksheets("Sheet1")
With wsSheet
Set rnData = Range("A2:A" & Range("A" & Rows.Count).End(xlUp).Row)
End With"
Once again thank you for the help.
`Private Sub UserForm_Initialize()
Dim wsSheet As Worksheet
Dim rnData As Range
Dim vaData As Variant
Dim ncData As New VBA.Collection
Dim lnCount As Long
Dim vaItem As Variant
Set wsSheet = Worksheets("Sheet1")
With wsSheet
Set rnData = Range("A2:A" & Range("A" & Rows.Count).End(xlUp).Row)
End With
vaData = rnData.Value
On Error Resume Next
For lnCount = 1 To UBound(vaData)
ncData.Add vaData(lnCount, 1), CStr(vaData(lnCount, 1))
Next lnCount
On Error GoTo 0
With ComboBox1
.Clear
For Each vaItem In ncData
.AddItem ncData(vaItem)
Next vaItem
End With
End Sub
Private Sub CommandButton1_Click()
Dim c As Range
With Range("B2:B" & Range("B" & Rows.Count).End(xlUp).Row)
Set c = .Find(ComboBox2.Value, LookIn:=xlValues)
c.Activate
ActiveCell.EntireRow.Copy
Sheets("Sheet2").Select
RowCount = Cells(Cells.Rows.Count, "a").End(xlUp).Row
Range("a" & RowCount + 1).Select
ActiveSheet.Paste
Application.CutCopyMode = False
End With
Sheets("Sheet1").Select
Range("a1").Select
Unload Me
End Sub
Private Sub ComboBox1_Change()
Dim cell As Range
Me.ComboBox2.Clear
For Each cell In Range("A2:A" & Range("A" & Rows.Count).End(xlUp).Row)
If cell.Value = Me.ComboBox1 Then
Me.ComboBox2.AddItem (cell.Offset(0, 1).Value)
End If
Next cell
Me.ComboBox2.ListIndex = 0
End Sub`

Answer 1

Might be this typo (you are missing the dots before the two ranges):
With wsSheet
Set rnData = .Range("A2:A" & .Range("A" & Rows.Count).End(xlUp).Row)
End With
And as rory pointed out in the comments above, check if you are addressing the correct workbook. Maybe add this to be safe:
Set wsSheet = ThisWorkbook.Worksheets("Sheet1")