Crystal reports 我能'；不要在crystal report中显示任何结果

我正在开发一个web应用程序，无法在crystal report中显示任何结果。我不知道我的代码出了什么问题。请帮忙

    Dim cnn As SqlConnection
    Dim connectionString As String
    Dim sql As String
    connectionString = "data source=SERVERNAME; _
    initial catalog=crystaldb;user id=sa;password=PASSWORD;"
    cnn = New SqlConnection(connectionString)
    cnn.Open()
    sql = "SELECT * FROM Grades
    Dim dscmd As New SqlDataAdapter(sql, cnn)
    Dim ds As New DataSet1
    dscmd.Fill(ds, "Grades")
    objRpt.SetDataSource(ds.Tables(1))
    CrystalReportViewer1.ReportSource = objRpt
    CrystalReportViewer1.RefreshReport()

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我在加载时也遇到了很多问题，请尝试这些链接。[或者试试这个]（）