data grid to xml file using vb.net

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VB

XML

data in datagrid should be saved in separate file.
the file must show daily data where user entered in data grid
with this code the data in xml file is overwriting the old one and showing only new file.
please help me.

Public Sub SwipeDTBind(ByVal EmplId As String)
        Try
            Dim ds As DataSet
            ds = New DataSet
            ds.Clear()
            ds.ReadXml("EmployeeTimeCard_1.XML")

            Dim dtbl As DataTable = ds.Tables(0)

            ds.Tables(0).DefaultView.Sort = "EmployeeId DESC"

            Dim dv As DataView = New DataView(dtbl)
            dv.RowFilter = "EmployeeId = '" & EmplId & "'"
            dv.Sort = "LoginTime"
            dtbl.Columns(0).ColumnMapping = MappingType.Hidden

            dtbl.Columns(1).ColumnMapping = MappingType.Hidden
            ds.WriteXml("E:\Syscom\EmployeeTimeCard\EmployeeTimeCard_1.XML", XmlWriteMode.IgnoreSchema)
            dgSwipedt.DataSource = dv

        Catch ex As Exception
            Me.ErrorLog(ex.Message.ToString())
        End Try
    End Sub