Problems With SqlDataAdapter

I'm working on a project to dynamically create PDFs with content from an SQL server. My current approach is to get the data I need into a DataSet using SqlDataAdapter, write the DataSet to a stream as XML, transform the XML into FO and then output a pdf using FOP. For some reason I get the following exception "System.NullReferenceException - Object reference not set to an instance of an object" when I try to set the SelectCommand property of my data adapter. Code for the project follows:

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim con As SqlConnection
        Dim cmd As SqlCommand
        Dim IDlist As String
        Dim keyidary As Array
        Dim query As String
        Dim tempxml As Stream

        query = "*****query is valid and very long, so it's not included here*****"

        IDlist = Request.Form("chosenIDs")

        keyidary = Split(IDlist, ",")
        Dim makequery As New StringBuilder(query)

        For Each ID As String In keyidary
            makequery.Append(" OR (KeyID = '" & ID & "')")
        Next

        query = makequery.ToString()

        'Response.Write(query)         When uncommented this prints the query just fine
        'Response.End()

        Try
            con = New SqlConnection
            con.ConnectionString = "****Connection String is valid****"

            cmd = New SqlCommand
            cmd.CommandText = query
            cmd.CommandType = CommandType.Text
            cmd.Connection = con

            Dim adpt As SqlDataAdapter
            adpt.SelectCommand = cmd

            'Response.Write(query)          When these are above or between the previous 2 statements, query is printed,
            'Response.End()                     otherwise I get the error described above.

            Dim profiles As New DataSet
            adpt.Fill(profiles)
            profiles.WriteXml(tempxml)

            Dim step1 As XslTransform = New XslTransform
            Dim step2 As XslTransform = New XslTransform
            step1.Load(Server.MapPath("TransAttmpt1.xslt"))
            step2.Load(Server.MapPath("formatXML.xsl"))

            Dim xml, pdf As String
            xml = "profiles.xml"
            pdf = "Profiles.pdf"

            Dim temp2xml As New XPathDocument(tempxml)

            Response.Write(query)
            Response.End()
            Dim midstream As Stream
            Dim finalxml As StreamWriter = New StreamWriter(xml)


            step1.Transform(temp2xml, Nothing, midstream, Nothing)
            Dim xpathdoc2 As XPathDocument = New XPathDocument(midstream)

            step2.Transform(xpathdoc2, Nothing, finalxml, Nothing)
            GeneratePDF(xml, pdf)
        'There's a lot more but it doesn't seem relevant now....
 I'm somewhat at a loss on how to proceed and any help is very greatly appreciated.
Thanks!