document types insert error

<%@ Page Title="" Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="true" CodeFile="CustomerDocuments.aspx.cs" Inherits="CustomerDocuments" StylesheetTheme="Theme" %>

<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">

 <table>
    <tr>
    <td style="width:20%"></td>
    <td style="width:80%"><asp:Label ID="lblErr" runat="server" ForeColor="Red"></asp:Label></td>
    </tr>
    <tr>
    <td colspan="2" style="background-color:rgb(255, 233, 126)" >
        <asp:Label ID="Label2" runat="server" Text="New Document Types"
            style="font-weight: 700"></asp:Label>
    </td>
    </tr>
    <tr>
        <td><asp:Label ID="Label3" runat="server" Text="Document Type"></asp:Label></td>
        <td>
            <asp:TextBox ID="txtDocType" runat="server"></asp:TextBox>
        </td>
    </tr>
    <tr>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
    </tr>
    <tr>
        <td>&nbsp;</td>
        <td><asp:Button ID="btnSave0" runat="server" onclick="btnSave0_Click"
                Text="Save Document Type" />
            </td>
    </tr>
    <tr>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
    </tr>
    <tr>
    <td colspan="2" style="background-color:rgb(255, 233, 126)" >
        <asp:Label ID="Label1" runat="server" Text="Customer Associated Document Types"
            style="font-weight: 700"></asp:Label>
    </td>
    </tr>

    <tr>
        <td><asp:Label ID="Label4" runat="server" Text="Customers"></asp:Label></td>
        <td><asp:DropDownList ID="ddlCustomers" runat="server"  BackColor='AliceBlue' Width=218px
                    DataSourceID="Customers" DataTextField="CustomerName"
            DataValueField="CustomerId" AutoPostBack="True">
                </asp:DropDownList></td>
    </tr>
    <tr>
        <td><asp:Label ID="Label5" runat="server" Text="Customer Type"></asp:Label></td>
        <td>
            <asp:DropDownList ID="ddlDocumentTypes" runat="server"
                DataSourceID="DocumentTypes" DataTextField="DocumentType"
                DataValueField="DocumentTypeId" Width="209px">
            </asp:DropDownList>
        </td>
    </tr>
    <tr>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
    </tr>
    <tr>
        <td>&nbsp;</td>
        <td><asp:Button ID="btnSave" runat="server" onclick="btnSave_Click" Text="Save" />
            </td>
    </tr>
    <tr>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
    </tr>
    <tr>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
    </tr>
    <tr>
        <td colspan="2">
            <asp:GridView ID="GridView1" runat="server" AllowPaging="True"
                AllowSorting="True" AutoGenerateColumns="False" DataSourceID="CustomerDocumentTypes"
                EnableModelValidation="True" SkinID="GridListView"
                EmptyDataText="Customer has no document types associated">
                <Columns>
                    <asp:BoundField DataField="DocumentType"
                        HeaderText="Customer Document Types"
                        SortExpression="DocumentType" />
                </Columns>
            </asp:GridView>
        </td>
    </tr>
    <tr>
        <td>&nbsp;</td>
        <td>


    <asp:SqlDataSource ID="Customers" runat="server"
        ConnectionString="<%$ ConnectionStrings:SecurityDB_20101025ConnectionString %>"

 SelectCommand="SELECT * FROM [Customers] WHERE ([CustomerId] = ISNULL(@CustomerId, '') OR @IsSuperAdmin = 1 )
 order by customername
  "
        >
        <SelectParameters>
            <asp:SessionParameter Name="CustomerId" SessionField="CustomerID"
                />
                <asp:SessionParameter Name="IsSuperAdmin" SessionField="IsSuperAdmin" Type="Boolean"
                />

        </SelectParameters>
    </asp:SqlDataSource>
            <asp:SqlDataSource ID="DocumentTypes" runat="server"
                ConnectionString="<%$ ConnectionStrings:SecurityDB_20101025ConnectionString %>"

                SelectCommand="SELECT * FROM [DocumentTypes]
WHERE DocumentTypeId NOT IN ( Select DocumentTypeId from CustomerDocumentTypes WHERE CustomerId = @CustomerId)" InsertCommand="INSERT INTO [DocumentTypes]
(DocumentType)
VALUES
(@DocumentType)">
                <InsertParameters>
                    <asp:ControlParameter ControlID="txtDocType" Name="DocumentType" PropertyName="Text"  />
                </InsertParameters>
                <SelectParameters>
                    <asp:ControlParameter ControlID="ddlCustomers" Name="CustomerId"
                        PropertyName="SelectedValue" />
                </SelectParameters>
            </asp:SqlDataSource>
            <asp:SqlDataSource ID="CustomerDocumentTypes" runat="server"
                ConnectionString="<%$ ConnectionStrings:SecurityDB_20101025ConnectionString %>"
                SelectCommand="SELECT D.DocumentType FROM [CustomerDocumentTypes]  C
INNER JOIN DocumentTypes D
ON C.DocumentTypeID = D.DocumentTypeID
WHERE ([CustomerId] = @CustomerId)" InsertCommand="INSERT INTO CustomerDocumentTypes
(CustomerID, DocumentTypeId)
VALUES
(@CustomerId, @DocumentTypeId)">

                <SelectParameters>
                    <asp:ControlParameter ControlID="ddlCustomers" Name="CustomerId"
                        PropertyName="SelectedValue" Type="Int32" />
                </SelectParameters>
                <InsertParameters>
                    <asp:ControlParameter ControlID="ddlCustomers" Name="CustomerId"
                        PropertyName="SelectedValue" Type="Int32" />
                        <asp:ControlParameter ControlID="ddlDocumentTypes" Name="DocumentTypeId"
                        PropertyName="SelectedValue" Type="Int32" />
                </InsertParameters>
            </asp:SqlDataSource>
            <br />
        </td>
    </tr>
    </table>
</asp:Content>