Incompatibilité de type

Private Sub search()
    Dim nb_boucle As Long, count_gene As Long
    Dim Dico_Data As Object, Plage As Variant, TMP, x As Long, List_Gene As String

    'fige ecran
    Application.ScreenUpdating = False
    Nom_Class = ThisWorkbook.Name
    'raz liste,
    Set Dico_Data = CreateObject("Scripting.Dictionary")
    
    'boucle sur les onglets
    With Workbooks("Classeur2.xlsx").Worksheets("feuil1")
        derlig = .Range("A" & Rows.Count).End(xlUp).Row   'derniere cellule non vide colonne A
        Plage = .Range("A1:A" & derlig)                               'mise en memoire
        'boucle sur plage
        For x = 1 To UBound(Plage, 1)
            Dico_Data(Plage(x, 1)) = ""     'mise en memoire plage de gene colonne A
        Next x
    End With
    With Workbooks(Nom_Class).Worksheets("feuil2")
        derlig = .Range("A" & Rows.Count).End(xlUp).Row   'derniere cellule non vide colonne A
        Plage = .Range("A1:A" & derlig)                               'mise en memoire
        'boucle sur plage
        nb_boucle = UBound(Plage, 1)    'longueur plage
        For x = 1 To UBound(Plage, 1)   'boucle plage
            If Dico_Data.exists(Plage(x, 1)) Then   'gene indentique ??
                'ecriture liste
                List_Gene = List_Gene & Chr(9) & Plage(x, 1) & vbNewLine
                count_gene = count_gene + 1
            End If
        Next x
    End With
    MsgBox "j'ai fait " & nb_boucle & " tours de boucle dans la feuille 2" & vbNewLine & _
             "j'ai compté " & count_gene & " gènes identiques." & vbNewLine & _
             "Liste genes:" & vbNewLine & List_Gene
             
    Set Dico_Data = Nothing
    Set Plage = Nothing
End Sub