Select Method of Range Class Failed

Hi,

I'm trying to write a code such that when the user presses the button GRAPH, it graphs the data in the file for each column
Capture.PNG

I run into a debug error on this line:

Range(Cells(1, NCol), Cells(LastRow, NCol)).Select

Full code:

Private Sub cmdGraph_Click()

    gFolderpath.Text = chkLastChar(gFolderpath.Text)
    ChDir gFolderpath.Text
    Workbooks.Open Filename:=gFolderpath.Text & gFilename
    
    
    Dim nLeft As Long, nTop As Long
    Dim strChrt As String
    
    LastRow = ActiveSheet.Cells(Rows.Count, 1).End(xlUp).Row
    LastCol = ActiveSheet.Cells(1, Columns.Count).End(xlToLeft).Column
        
    nLeft = 20: nTop = 0
        
    For NCol = 1 To LastCol
            
        Range(Cells(1, NCol), Cells(LastRow, NCol)).Select
        ActiveSheet.Shapes.AddChart2(227, xlLine).Select
        ActiveChart.SetSourceData Source:=Range(Cells(1, NCol), Cells(LastRow, NCol))
        
        strChrt = Trim(Replace(ActiveChart.Name, ActiveSheet.Name, ""))
            
        ActiveSheet.Shapes(strChrt).Left = nLeft
        ActiveSheet.Shapes(strChrt).Top = nTop
            
        '~~> Increment the next `Top` placement for the chart
        nTop = nTop + ActiveSheet.Shapes(strChrt).Height + 20
            
    Next NCol
    
End Sub

It's weird because I wrote this code before and it worked before. Now I'm trying to modify it responds through a button on a form so that it is more user friendly.
This is my old code that worked. I can't seem to see the difference.

Sub MergeWorkbooks_V2()

    Dim NCol As Long
    Dim NRow As Long
    Dim LastRow As Long
    Dim LastCol As Long
    Dim NSheets As Long
    Dim LastSheet As Integer
    
    ' Modify this folder path to point to the files you want to use.
    FolderPath = "C:\Users\VCHU\Desktop\Sample_LTE_0021_3-1261\"
    FileName = Dir(FolderPath & "Sheet1.xlsx")

    ' Call Dir the first time, pointing it to all Excel files in the folder path.
    FileName = Dir(FolderPath & "Sheet1.xlsx")
    
    ' Open a workbook in the folder
    Set WorkBk = Workbooks.Open(FolderPath & FileName)
    
    ' Number of sheets
    LastSheet = 2
    
    Dim nLeft As Long, nTop As Long
    Dim strChrt As String
    
    For NSheets = 1 To LastSheet
        Sheets(NSheets).Select
        LastRow = ActiveSheet.Cells(Rows.Count, 1).End(xlUp).Row
        LastCol = ActiveSheet.Cells(1, Columns.Count).End(xlToLeft).Column
        
        nLeft = 20: nTop = 0
        
        For NCol = 1 To LastCol
            
            Range(Cells(1, NCol), Cells(LastRow, NCol)).Select
            ActiveSheet.Shapes.AddChart2(227, xlLine).Select
            ActiveChart.SetSourceData Source:=Range(Cells(1, NCol), Cells(LastRow, NCol))
        
            strChrt = Trim(Replace(ActiveChart.Name, ActiveSheet.Name, ""))
            
            ActiveSheet.Shapes(strChrt).Left = nLeft
            ActiveSheet.Shapes(strChrt).Top = nTop
            
            '~~> Increment the next `Top` placement for the chart
            nTop = nTop + ActiveSheet.Shapes(strChrt).Height + 20
            
        Next NCol
    
    Next NSheets
    
End Sub

DataProcessing_Tool.xlsm