Try
 
                Dim conStr As String = "Provider=Microsoft.Jet.OLEDB.4.0; Data" & _
                  "Source=DB-PBW.mdb;"
                Dim conn As New OleDbConnection(conStr)
 
                Dim selStr As String = "SELECT HiPlKey FROM HiPl WHERE" & _
                  "HiPlKLientKeyFremd = @Klkey AND @Enddatum BETWEEN" & _
                  "HiPlKostenübernahmeab AND HiPlKostenübernahmebis"
                Dim da As New OleDbDataAdapter(selStr, conn)
 
                da.SelectCommand.Parameters.Add("@Klkey", _
                  OleDbType.Numeric).Value = Me.txtKlientKeyfremd.Text
                da.SelectCommand.Parameters.Add("@Enddatum", _
                OleDbType.DBDate).Value = CDate(lblMonat.Text)
 
                Dim dt As New DataTable("HiPl")
                conn.Open()
                da.Fill(dt)
                Me.lblHPAKey.DataBindings.Add("Text", dt, "HiPlKey")
                conn.Close()
 
 
            Catch ex As Exception
                MessageBox.Show(ex, "Hinweis")
            End Try