merci Bruno
j'ai trouve
en fait ton code initial fonctionnait très bien. c'est mon fichier test qui avait un problème
voici donc le code qui fonctionne chez moi
merci bcp ; sans ton aide j'étais bloqué
BONNES VACANCES 
***
Option Explicit
Dim I, II, III, IV
Dim Ws As Worksheet
Dim WsBL As Worksheet
Dim WsPLBL As Worksheet
Dim WsCM As Object
Dim WsMR As Worksheet
Sub NEWblmobile()
I = 0: II = 0: III = 0: IV = 0
Application.ScreenUpdating = False
With ActiveWorkbook
   .Unprotect ("")
For Each Ws In .Worksheets
With Ws
  Select Case True
         Case .Name Like "Mobile BL*"
          I = I + 1
         Case .Name Like "Packing List BL*"
         II = II + 1
         Case .Name Like "Mobile CM*"
        III = III + 1
         Case .Name Like "Mobile MR*"
        IV = IV + 1
  End Select
End With
Next Ws
        .Sheets("Mobile BL1").Copy after:=.Sheets(.Sheets.Count)
  Set WsBL = ActiveSheet
     With WsBL
        .Name = "Mobile BL" & 1 + I
      End With
        .Sheets("Packing List BL1").Copy after:=.Sheets(.Sheets.Count)
  Set WsPLBL = ActiveSheet
     With WsPLBL
        .Name = "Packing List BL" & 1 + II
        .UsedRange.Replace What:="Mobile BL" & II, Replacement:=WsBL.Name, LookAt:=xlPart, _
           SearchOrder:=xlByRows, MatchCase:=False, SearchFormat:=False, _
              ReplaceFormat:=False
     End With
     Sheets("Mobile CM1").Unprotect
             .Sheets("Mobile CM1").Copy after:=.Sheets(.Sheets.Count)
  Set WsCM = ActiveSheet
     With WsCM
        .Name = "Mobile CM" & 1 + III
        .UsedRange.Replace What:="Mobile BL" & II, Replacement:=WsBL.Name, LookAt:=xlPart, _
           SearchOrder:=xlByRows, MatchCase:=False, SearchFormat:=False, _
              ReplaceFormat:=False
     End With
     Sheets("Mobile MR1").Unprotect
             .Sheets("Mobile MR1").Copy after:=.Sheets(.Sheets.Count)
    Set WsMR = ActiveSheet
     With WsMR
        .Name = "Mobile MR" & 1 + IV
        .UsedRange.Replace What:="Mobile BL" & IV, Replacement:=WsBL.Name, LookAt:=xlPart, _
           SearchOrder:=xlByRows, MatchCase:=False, SearchFormat:=False, _
              ReplaceFormat:=False
     End With
    
End With
Application.ScreenUpdating = True
ActiveWorkbook.Protect ("")
End Sub
***