VBA to actvate Unfilter after Auto Filter

Hi All,

I have pieced together the below code to autofilter a workbook based on the cell entry in Sheet 1, A1. The code works great whilst sorting the information, but has a run time error when entry is " ", this entry should unsort all infomation in the previously sorted sheets.
I would also like the first two sheets excluded from the sort and the code to run on the cell change.

Sub DoFilters()
    Dim w As Worksheet, RLetter As String
    Dim Crit    As String
    Crit = Sheets("Sheet1").Range("A1").Value
    RLetter = Crit
    For Each w In Worksheets
    
    If RLetter = "" Then w.Cells.AutoFilter
    w.Range("A:A").AutoFilter.false
    
    If w.FilterMode Then w.Cells.AutoFilter
    w.Range("A:A").AutoFilter Field:=1, Criteria1:=Crit

    Next
End Sub

Any help is much appreciated

Cheers

Adam