Code no longer Working, Error 91

Hi,

I have a spreadsheet that uses this code on one of the sheets. It's used for charting a row of variables based on what row you click on. It can also chart based on what row you select with the up and down arrows (spinbuttons). Basically I have a row of variables and I load that row into the chart. The row is selected via CR7. The variables in the row are loaded using the "=INDIRECT("X"&$CR7)". I don't know what changed but this used to work, now when I open the spread sheet I get Error 91. As far as I can tell it might be that chkRowClick_Click() is not being set to True but I can't tell where it gets set on the sheet. I didn't make this sheet or code so I'm hoping this is a simple fix if anyone can help?

Thanks

Private Sub chkRowClick_Click()

End Sub

Private Sub SpinButton1_SpinDown()
    With Range("CR7")
        .Value = WorksheetFunction.Max(0, .Value - 1)
    End With
    End Sub

Private Sub SpinButton1_SpinUp()
    With Range("CR7")
        .Value = WorksheetFunction.Max(0, .Value + 1)
    End With
End Sub

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
    'If chkRowClick.Value = "True" Then
        Dim PreviousRow As Integer
        PreviousRow = ActiveCell.Row
        Sheet24.Range("CR7").Value = PreviousRow
    'End If
End Sub