Help: Error = NullReferenceException was unhandled by user code

Any help would be appreciated... Code works cleanly until error...

Error occuring at line: SqlDataSource3.UpdateParameters("TechID").DefaultValue() = CInt(technicianRow("TechID"))

Here is full VB code:

Imports System.Data

Partial Class IncidentAssignment
    Inherits System.Web.UI.Page

    Public incidentRow As DataRowView
    Public technicianRow As DataRowView

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click

        'Check to see if a incident has been selected

        If GridView1.SelectedIndex = -1 Then
            Button1.CommandName = ""
            lblmessage.Text = "You must select an incident."

        Else
            Button1.CommandName = "NextView"
            lblmessage.Text = ""


        End If
    End Sub

    Protected Sub Button3_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button3.Click

        'Check to see if a incident has been selected

        If GridView2.SelectedIndex = -1 Then
            Button3.CommandName = ""
            lblmessage2.Text = "You must select a technician."

        Else
            Button3.CommandName = "NextView"
            lblmessage2.Text = ""
            'Create second DataView

            Dim techniciansTable As DataView = CType(SqlDataSource2.Select(DataSourceSelectArguments.Empty), DataView)


            'Save the selected technician data row

            'To the DataRowView object and to session state

            technicianRow = techniciansTable(GridView2.SelectedIndex)

            Session("Technician") = technicianRow

            'Create DataView

            Dim incidentsTable As DataView = CType(SqlDataSource1.Select(DataSourceSelectArguments.Empty), DataView)

            'Save PageIndex and PageSize to variables.

            Dim pageIndex As Integer = GridView1.PageIndex

            Dim pageSize As Integer = GridView1.PageSize



            'Calculate the value of the SelectedIndex

            Dim selectedIndex As Integer = (pageIndex * pageSize) + GridView1.SelectedIndex

            'Save the selected data row to the DataRowView

            'object and to session state

            incidentRow = incidentsTable(selectedIndex)

            Session("Incident") = incidentRow

            'Display output from the two DataRowView objects

            Label1.Text = incidentRow("Name")

            Label2.Text = incidentRow("ProductCode")

            Label3.Text = technicianRow("Name")

        End If

    End Sub



    Public Sub btnAssign_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnAssign.Click

        'Assign data from session state to

        'the two DataRowView objects

***ERROR technicianRow = CType(Session("Technician"), DataRowView)

        incidentRow = CType(Session("Incident"), DataRowView)


        'Update the value of the two parameters to be

        'used to store new information about the

        'assigned technician



        SqlDataSource3.UpdateParameters("TechID").DefaultValue() = CInt(technicianRow("TechID"))

        SqlDataSource3.UpdateParameters("IncidentID").DefaultValue() = CInt(incidentRow("IncidentID"))


        'Trap errors

        T开发者_Python百科ry

            'Update the table.

            SqlDataSource3.Update()



            'Unselect the two GridView controls

            GridView1.SelectedIndex = -1

            GridView2.SelectedIndex = -1


            'Rebind the GridView controls

            GridView1.DataBind()

            GridView2.DataBind()


            'Move to the first view

            MultiView1.ActiveViewIndex = 0

        Catch ex As Exception

            Session("Exception") = ex

            Session("Page") = "~/Admin/IndicentAssignment.aspx"

            Response.Redirect("~/ErrorMessage.aspx")

        End Try

    End Sub

    Protected Sub GridView2_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles GridView2.SelectedIndexChanged

    End Sub
End Class

---

Remove the parenthesis from ".DefaultValue()

do you have the parameters defined on the sqldatasource in the page??

UpdateParameters>
              <asp:Parameter Name="SomeName" Type="String" />
              <asp:Parameter Name="SomeDescription" Type="String" />
            </UpdateParameters>