Error occured when Crystal Report combine Main Report and Subreport

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VB

CrystalReports

I follow the article of the following link.
http://vb.net-informations.com/crystal-report/vb.net_crystal_report_subreport.htm

But I get an error as the following.
http://i.imgur.com/4MGeOsQ.jpg?1

I followed the steps to linking the the "id" field but it gave me the error.

Here is the code. (database.show(sql) is a function that return a datatable.)

Dim sql As String = "select oid as 'id', time as 'InvoiceDate', invoiceto as 'InvoiceNo', depost2 as 'Discount' from `order` limit 0,3"
Dim dtinv As DataTable = database.show(sql)

sql = "select oid as 'id', productbarcode as 'ItemCode', p.pname as 'ItemName', p.cost as 'Cost', p.dprice as 'UnitPrice', qty as 'Qty', extendedprice as 'TotalAmount' from suborder o left join `product` p on (o.productbarcode = p.pcode) where oid in ("

Dim o As String = ""

For Each row As DataRow In dtinv.Rows
       If o.Length > 0 Then
            o &= " ," & row.Item("id")
       Else
            o &= row.Item("id")
       End If
Next

sql &= o & ")"

Dim dt As DataTable = database.show(sql)

Dim crystalReport As ReportDocument = New ReportDocument()
crystalReport.Load("./SalesOrderReport.rpt")
crystalReport.SetDataSource(dtinv)
crystalReport.Subreports(0).SetDataSource(dt)

CrystalReportViewer1.ReportSource = crystalReport

The "dtinv" table should be as the following.

id  InvoiceDate         InvoiceNo   Discount
35  2014-12-08 14:36:16 IAN000035   0
36  2014-12-08 14:44:13 IAN000036   0
37  2014-12-08 14:48:35 IAN000037   0

The "dt" table should be as the following.

id	ItemCode	ItemName	Cost	UnitPrice	Qty	TotalAmount
35	108	Pureness 100 Placenta Mask Sheet Strengthening Ski...	50	100	1	100.00
35	3	Pure Water Baobab Moist Cream	50	100	1	100.00
36	3	Pure Water Baobab Moist Cream	50	100	1	100.00
37	5	Aloe Moistfull Soothing Lotion	50	100	1	100.00

Please help me and give me some advise to solve this problem. Thanks a lot.