Run-time error '1004': Method 'Range' of object '_ Global' failed

Hi,
I am very new to VBA and am looking at a former colleague's worksheet. There is a macro in this worksheet which automatically creates 3 additional blank rows near the bottom of a spreadsheet.

Unfortunately this macro does not seem to be working any more. I have copied the code for the macro below.

Sub Insert_Row()
 
    Application.ScreenUpdating = False
    Application.DisplayAlerts = False

        Worksheets("Detailed").Select
        ActiveSheet.Unprotect Password:=PW
        Range("DetIR").Offset(-1, 0).EntireRow.Hidden = False
        Range("DetIR").Offset(-1, 0).EntireRow.Copy
        Range("DetIRRange").Insert Shift:=xlDown
        Range("DetIR").Offset(-1, 0).EntireRow.Hidden = True
        
        Worksheets("Summary").Select
        ActiveSheet.Unprotect Password:=PW
        Range("SumIR").Offset(-1, 0).EntireRow.Hidden = False
        Range("SumIR").Offset(-1, 0).EntireRow.Copy
        Range("SumIRRange").Insert Shift:=xlDown
        Range("SumIR").Offset(-1, 0).EntireRow.Hidden = True
        Range("A1").Select
        ActiveSheet.Protect Password:=PW
        
        Worksheets("Detailed").Select
        Range("A1").Select
        ActiveSheet.Protect Password:=PW
        
    Application.CutCopyMode = False
    
    Application.ScreenUpdating = True
    Application.DisplayAlerts = True



End Sub

The row that the debugger selects as causing the error is:

Range("SumIR").Offset(-1, 0).EntireRow.Hidden = False

Any help will be very gratefully received.

Thanks