Sub testTER()
Dim wbk As Workbook, tWbk As Workbook, ws As Worksheet, flag As Boolean
Set tWbk = ThisWorkbook
For Each wbk In Workbooks
If wbk.Name Like "agenc*" Then flag = True: Exit For
Next wbk
If flag = False Then
MsgBox "Le fichier n'a pas été trouvé!", vbCritical, "Fichier non ouvert"
Exit Sub
Else
For Each ws In wbk.Worksheets
ws.Copy after:=tWbk.Sheets(tWbk.Sheets.Count)
Next ws
End If
End Sub