System.NullReferenceException: Object reference not set to an instance of an object for Datakeys in GridView RowCommand using VB.Net in ASP.Net

resi says:

 Dim CurrentRow As GridViewRow = TryCast(ctl.NamingContainer, GridViewRow)

        Dim thn As Integer = GridView2.DataKeys(CurrentRow.RowIndex)(0)

        Dim bln As Integer = GridView2.DataKeys(CurrentRow.RowIndex)(1)

 

 

        If e.CommandName = "ShowAccount" Then

 

            Dim id As String = e.CommandArgument.ToString

            'tampil grid

            Dim cmd As New SqlCommand()

            Dim adapter As New SqlDataAdapter()

            Dim ds As New DataSet()

            Dim i As Integer = 0

            Dim sql As String = Nothing

            con.Open()

            cmd.Connection = con

            cmd.CommandType = CommandType.StoredProcedure

            cmd.CommandText = "ShowTotalAccount"

            cmd.Parameters.Add("@Id", SqlDbType.Int).Value = id

            '  @year int, @month int

            cmd.Parameters.Add("@year", SqlDbType.Int).Value = thn

            cmd.Parameters.Add("@month", SqlDbType.Int).Value = bln

            '    cmd.Parameters.AddWithValue("@id_customer_info", Integer.Parse(lblCustomerID.Text.Trim))

            adapter = New SqlDataAdapter(cmd)

            adapter.Fill(ds)

            con.Close()

            GridView3.DataSource = ds.Tables(0)

            GridView3.DataBind()

        ElseIf e.CommandName = "ShowLead" Then

            Dim id As String = e.CommandArgument.ToString

            'tampil grid

            Dim cmd As New SqlCommand()

            Dim adapter As New SqlDataAdapter()

            Dim ds As New DataSet()

            Dim i As Integer = 0

            Dim sql As String = Nothing

            con.Open()

            cmd.Connection = con

            cmd.CommandType = CommandType.StoredProcedure

            cmd.CommandText = "ShowTotalLead"

            cmd.Parameters.Add("@Id", SqlDbType.Int).Value = id

            cmd.Parameters.Add("@year", SqlDbType.Int).Value = thn

            cmd.Parameters.Add("@month", SqlDbType.Int).Value = bln

            '    cmd.Parameters.AddWithValue("@id_customer_info", Integer.Parse(lblCustomerID.Text.Trim))

            adapter = New SqlDataAdapter(cmd)

            adapter.Fill(ds)

            con.Close()

            GridView3.DataSource = ds.Tables(0)

            GridView3.DataBind()

        ElseIf e.CommandName = "ShowOwner" Then

            Dim id As String = e.CommandArgument.ToString

            'tampil grid

            Dim cmd As New SqlCommand()

            Dim adapter As New SqlDataAdapter()

            Dim ds As New DataSet()

            Dim i As Integer = 0

            Dim sql As String = Nothing

            con.Open()

            cmd.Connection = con

            cmd.CommandType = CommandType.StoredProcedure

            cmd.CommandText = "ShowTotalOwner"

            cmd.Parameters.Add("@Id", SqlDbType.Int).Value = id

            cmd.Parameters.Add("@year", SqlDbType.Int).Value = thn

            cmd.Parameters.Add("@month", SqlDbType.Int).Value = bln

            '    cmd.Parameters.AddWithValue("@id_customer_info", Integer.Parse(lblCustomerID.Text.Trim))

            adapter = New SqlDataAdapter(cmd)

            adapter.Fill(ds)

            con.Close()

            GridView3.DataSource = ds.Tables(0)

            GridView3.DataBind()

 

            GridView3.DataBind()

        ElseIf e.CommandName = "ShowActivity" Then

            Response.Write("<script language=javascript>alert('ERROR ShowActivity');</script>")

        ElseIf e.CommandName = "ShowDeal"

            Response.Write("<script language=javascript>alert('ERROR ShowDeal');</script>")

        End If

 replace above code with below.

    Dim CurrentRow As GridViewRow = TryCast(ctl.NamingContainer, GridViewRow)
    If Not CurrentRow Is Nothing Then
    Dim thn As Integer = GridView2.DataKeys(CurrentRow.RowIndex)(0)
    Dim bln As Integer = GridView2.DataKeys(CurrentRow.RowIndex)(1)


    If e.CommandName = "ShowAccount" Then

    Dim id As String = e.CommandArgument.ToString
    'tampil grid
    Dim cmd As New SqlCommand()
    Dim adapter As New SqlDataAdapter()
    Dim ds As New DataSet()
    Dim i As Integer = 0
    Dim sql As String = Nothing
        con.Open()
        cmd.Connection = con
        cmd.CommandType = CommandType.StoredProcedure
        cmd.CommandText = "ShowTotalAccount"
        cmd.Parameters.Add("@Id", SqlDbType.Int).Value = id
    '  @year int, @month int
        cmd.Parameters.Add("@year", SqlDbType.Int).Value = thn
        cmd.Parameters.Add("@month", SqlDbType.Int).Value = bln
    '    cmd.Parameters.AddWithValue("@id_customer_info", Integer.Parse(lblCustomerID.Text.Trim))
        adapter = New SqlDataAdapter(cmd)
        adapter.Fill(ds)
        con.Close()
        GridView3.DataSource = ds.Tables(0)
        GridView3.DataBind()
    ElseIf e.CommandName = "ShowLead" Then
    Dim id As String = e.CommandArgument.ToString
    'tampil grid
    Dim cmd As New SqlCommand()
    Dim adapter As New SqlDataAdapter()
    Dim ds As New DataSet()
    Dim i As Integer = 0
    Dim sql As String = Nothing
        con.Open()
        cmd.Connection = con
        cmd.CommandType = CommandType.StoredProcedure
        cmd.CommandText = "ShowTotalLead"
        cmd.Parameters.Add("@Id", SqlDbType.Int).Value = id
        cmd.Parameters.Add("@year", SqlDbType.Int).Value = thn
        cmd.Parameters.Add("@month", SqlDbType.Int).Value = bln
    '    cmd.Parameters.AddWithValue("@id_customer_info", Integer.Parse(lblCustomerID.Text.Trim))
        adapter = New SqlDataAdapter(cmd)
        adapter.Fill(ds)
        con.Close()
        GridView3.DataSource = ds.Tables(0)
        GridView3.DataBind()
    ElseIf e.CommandName = "ShowOwner" Then
    Dim id As String = e.CommandArgument.ToString
    'tampil grid
    Dim cmd As New SqlCommand()
    Dim adapter As New SqlDataAdapter()
    Dim ds As New DataSet()
    Dim i As Integer = 0
    Dim sql As String = Nothing
        con.Open()
        cmd.Connection = con
        cmd.CommandType = CommandType.StoredProcedure
        cmd.CommandText = "ShowTotalOwner"
        cmd.Parameters.Add("@Id", SqlDbType.Int).Value = id
        cmd.Parameters.Add("@year", SqlDbType.Int).Value = thn
        cmd.Parameters.Add("@month", SqlDbType.Int).Value = bln
    '    cmd.Parameters.AddWithValue("@id_customer_info", Integer.Parse(lblCustomerID.Text.Trim))
        adapter = New SqlDataAdapter(cmd)
        adapter.Fill(ds)
        con.Close()
        GridView3.DataSource = ds.Tables(0)
        GridView3.DataBind()

        GridView3.DataBind()
    ElseIf e.CommandName = "ShowActivity" Then
        Response.Write("<script language=javascript>alert('ERROR ShowActivity');</script>")
    ElseIf e.CommandName = "ShowDeal"
        Response.Write("<script language=javascript>alert('ERROR ShowDeal');</script>")
    End If
End