Excel VBA - copy current month's column then insert in the next column to make new month

[ajm]

Hi folks,

Each month end, I create a copy of the last month's end file. as part of this process, all Report sheets (those that are sent out to the business) have the new month added to their tables. this is done by copying the previous month's (eg October) column, and inserting the copied cells in a new column adjacent to it. the previous month's formulas are then converted to values before the new month's raw data is imported.

I currently use this button fired routine to copy the whole column:

Private Sub CommandButton1_Click()
    Dim R As Range, BeforeR As Long

'Find 'Totals' in row 5 of active sheet
Set R = Rows(5).Find(what:="Totals", lookat:=xlWhole)

'identify the column to copy (last month)
BeforeR = R.Column - 1
    
    If R Is Nothing Then
      MsgBox ("The word 'Totals' was not found in Row 5 - macro terminated!")
        Exit Sub
    ElseIf Not R Is Nothing Then
    
    'copy last month's column
    Columns(BeforeR).Copy
    
    'insert copied cells before the Totals column
    Columns(R.Column).Insert Shift:=xlRight
    
    'change last month's column to values
        With Columns(BeforeR)
        .Value = .Value
        End With
 
    Application.CutCopyMode = False
    End If
    End Sub

On a separate sheet with a different layout, I want to do the same sort of thing but with only a range, rather than the whole column.

Private Sub CommandButton6_Click()
    Dim P As Range, BeforeP As Long, LstMth As Range
    
'Find 'Totals' in row 5 of active sheet
Set P = Rows(34).Find(what:="Totals", lookat:=xlWhole)
'MsgBox P.Address 'H34

'identify the column to copy (last month)
BeforeP = P.Column - 1
Set LstMth = ActiveSheet.Range(Cells(31, BeforeP), Cells(500, BeforeP)) '''copy G31:G500
'MsgBox BeforeP
    
    If P Is Nothing Then
      MsgBox ("The word 'Totals' was not found in Row 5 - macro terminated!")
        Exit Sub
    ElseIf Not P Is Nothing Then
    
    'copy last month's column
    LstMth.Copy
    
    'insert copied cells before the Totals column
    ActiveSheet.Cells(31, P.Column).Insert Shift:=xlRight  '''insert H31
    
    'change last month's column to values
        With LstMth
        .Value = .Value
        End With
 
    Application.CutCopyMode = False
    End If
    End Sub

This routine errors out at the insertion point. That is, at:

 'insert copied cells before the Totals column
    ActiveSheet.Cells(31, P.Column).Insert Shift:=xlRight

"Run time error 1004: Application defined or object defined error"

what syntax should i be using to get the current month range to copy into the adjacent range?