Run-time error '91' while using Find

The code continues beyond what I put in here but it is not important. When the code reaches the dataobj.range line of code, I get this error. Any ideas why it is happening?

Sub stacknew()

Dim dataobj As Object
Dim start
Dim newstart
Dim finish
Dim stackx
Dim X As Double
Dim c As Double
Dim i As Double
Dim keepx
Dim nsheet
Dim Data As String


 'printobj.Activate
  
    Set dataobj = ActiveWorkbook.ActiveSheet
  
  'goes to the specified subroutines and identifies the last row and column in the sheet
  X = lastrowN()
  c = lastcolN()
  
  'This loop is designed to be flexible with changes to the columns leading the raw data.
  'So that the leadig column is always the column with the "SD-1" header
    Data = "SD-1"
    start = 1
    'For p = 1 To c
      ' If dataobj.Cells(1, p) <> Data Then p = p + 1

        dataobj.Range(Cells(1, 1), Cells(1, c)).Find("SD-1", LookIn:=xlFormulas, LookAt:=xlWhole).Activate
        If Err.Number = 0 Then
            FTemp = dataobj.Cells(ActiveCell.Row, DataCol).Address
        Else
            FTemp = "???"
        End If