Probleme de récupération d'information via un WebService

Bonsoir à tous,

Voila, j'ai un petit souci.
Je suis en train de faire mon 1er WebService et je rencontre un problème.

Le WebService me permet d'executer des requêtes

Public Class Acces_Base_Support :Inherits WebService

    'Déclaration de la chaine de connexion
    Dim Acces_Base_Pai as string = "DRIVER={MySQL ODBC 3.51 Driver};" & _
                                    "SERVER=127.0.0.1;" & _
                                    "DATABASE=........;" & _
                                    "UID=.......;" & _
                                    "PASSWORD=.........;" & _
                                    "OPTION=3;"

    Public BaseSupport_Pai as OdbcConnection
    Public Msg_Connexion as string

    Function Etat_Connexion_Base_Pai as boolean
        Try
            BaseSupport_Pai.Open()
        Catch ex As Exception
            Etat_Connexion_Base_Pai = False
            Msg_Connexion = ex.message
        Finally
            Etat_Connexion_Base_Pai = True
        End Try
    End Function

    <WebMethod(Description:="Récupération des informations demandé via la requête sur la Base")> _
    Public Function Execute_Requete_Base_Pai(Requete As String,Table_Choisi as string) as DataSet
        BaseSupport_Pai = New OdbcConnection(Acces_Base_Pai)
        Dim Tableau as new DataSet
        If Etat_Connexion_Base_Pai = True then
            Try
                Dim myReader As new OdbcDataAdapter(Requete, BaseSupport_Pai)
                myReader.Fill(Tableau,"login")
                Return Tableau
            Catch ex as Exception
            ..........
    End Function
End Class

La compilation se fait sans probleme.
Ensuite je l'appel dans ma page .aspx

sub Page_Load(Obj as Object, E as EventArgs)
    Dim mb as new Acces_Base_Support
    Dim Requete as string = "Select * From login"
    Dim tab_recup as new DataSet

    Try
        DataGrid1.DataSource = mb.Execute_Requete_Base_Pai(Requete)
        DataGrid1.DataBind()
    Catch ex as Exception
        Label1.text = Ex.Message
    End Try
end sub

en retour j'ai: