[DotNetDevelopment] Problem in Inserting record to datagrid

[nag]

i am getting the following error while inserting record to db
Object reference not set to an instance of an object.
Line 70:         this.SqlDataSource1.InsertParameters
["projectname"].DefaultValue = companyName.Text;
 here is my code plz anyone help me
<ctMenu:ContextMenu ID="ContextMenu1" runat="server"
BackColor="#99CCCC" ForeColor="Maroon"
                OnItemCommand="ContextMenu1_ItemCommand"
RolloverColor="#009999" Width="111px" />

        <asp:SqlDataSource ID="SqlDataSource1" runat="server"
            ConnectionString="<%$
ConnectionStrings:durvaaConnectionString %>"
            SelectCommand="SELECT * FROM [dg_project]">
        </asp:SqlDataSource>

        <xGrid:xGrid ID="XGrid1" runat="server" AllowPaging="True"
AutoGenerateColumns="False" DataKeyNames="projectid"
            CellPadding="4" AllowSorting="True" BackColor="White"
BorderColor="#3366CC" BorderStyle="None"
            BorderWidth="1px" OnRowDeleting="XGrid1_RowDeleting"
MouseOverColor="0, 153, 153" OnFilterCommand="XGrid1_FilterCommand"
ContextMenuID="ContextMenu1" DescImage="~/App_Images/desc.gif"
AscImage="~/App_Images/asc.gif" OnRowClick="XGrid1_RowClick"
OnRowDoubleClick="XGrid1_RowDoubleClick" IsFiltered="True"
EnableRowClick="True">
            <Columns>
                <asp:TemplateField HeaderText="Manage Row">
                    <edititemtemplate>
                        <asp:LinkButton text="Update" runat="server"
id="lnkUpdate" CommandName="Update" CommandArgument='<% Bind
("projectname") %>' />&nbsp;&nbsp;
                        <asp:LinkButton text="Cancel" runat="server"
id="lnkCancel" CommandName="Cancel" />

</edititemtemplate>
                    <footertemplate>
                        <confirmControl:ConfirmLinkButton ID="lnkAdd"
runat="server" Text="Add" MessageText="Are you sure you want to add
this record?" OnClick="btnAdd_Click" />
                        <asp:LinkButton id="lnkCancelAdd"
runat="server" text="Cancel" OnClick="btnCancel_Click" />

</footertemplate>
                    <itemtemplate>
<asp:LinkButton id="lnkEdit" runat="server" __designer:wfdid="w1"
text="Edit" CommandName="Edit" CommandArgument='<% Bind("projectid")
%>'></asp:LinkButton>&nbsp;&nbsp; <confirmControl:ConfirmLinkButton
id="lnkDelete" runat="server" __designer:wfdid="w2"
CommandName="Delete" CommandArgument='<% Bind("projectid") %>'
Text="Delete" MessageText="Are you sure you want to delete this
record?"></confirmControl:ConfirmLinkButton>
</itemtemplate>
                </asp:TemplateField>

                <asp:TemplateField HeaderText="Company Name"
SortExpression="projectname">
                    <edititemtemplate>
                        <asp:TextBox id="txtEditCompanyName"
runat="server" Text='<%# Bind("projectname") %>'></asp:TextBox>

</edititemtemplate>
                    <footertemplate>
                        <asp:TextBox ID="txtCompanyName"
runat="server" />

</footertemplate>
                    <itemtemplate>
                        <asp:Label ID="lblCompanyName" runat="Server"><
%# Eval("projectname") %></asp:Label>

</itemtemplate>
                </asp:TemplateField>
            </Columns>

            <FooterStyle BackColor="#99CCCC" ForeColor="#003399" />
            <RowStyle BackColor="White" ForeColor="#003399" />
            <SelectedRowStyle BackColor="#009999" Font-Bold="True"
ForeColor="#CCFF99" />
            <PagerStyle BackColor="#99CCCC" ForeColor="#003399"
HorizontalAlign="Left" />
            <HeaderStyle BackColor="#003399" Font-Bold="True"
ForeColor="#CCCCFF" />
            <FilterStyle BackColor="#003399" ForeColor="#CCCCFF" Font-
Size="8pt" />
            <EmptyDataTemplate>
                No Data Available
            </EmptyDataTemplate>
        </xGrid:xGrid>

  protected void btnAdd_Click(object sender,EventArgs e)
    {
        TextBox companyName = this.XGrid1.FooterRow.FindControl
("txtCompanyName") as TextBox;
        this.SqlDataSource1.InsertParameters
["projectname"].DefaultValue = companyName.Text;
        this.SqlDataSource1.Insert();
        this.XGrid1.ChangeInsertMode(false);
    }