DetailsView with FileUpload Control

Question

hello friends
i need some help:
i have a form with detailsView controls bounded to an ObjectDataSource.
inside the detailsView i have some textBoxes, dropDownLists and FileUpload control.
now the ObjectDataSource has another class to handle the insert method.
without the fileUpload everting is ok, but when i try to insert the file upload to the InsertParameters of ObjectDataSource, its not working.
any help will be appreciated!
here is the code...

default.aspx:
<%--Data sources--%>
    <asp:ObjectDataSource runat="server" ID="ObjectDataSource1" TypeName="ShopLogic" SelectMethod="SelectShop" InsertMethod="InsertNewShop" >
     <InsertParameters>
     <asp:ControlParameter ControlID="FileUpload1" Type="Object" />
     </InsertParameters>
    </asp:ObjectDataSource>
 <%--Data sources--%>



    <%--details view--%>
        <asp:detailsview id="detailsview2" datasourceid="shopDataSource" autogeneraterows="false" runat="server" DefaultMode="Insert" >
        <fields>
             <asp:TemplateField HeaderText="title">
                  <InsertItemTemplate>
                      <asp:DropDownList ID="ddlTitle" runat="server" DataSourceID="ShopTitleDataSource" DataTextField="title"
                       DataValueField="title" SelectedValue='<%# Bind("title") %>' ></asp:DropDownList>
                  </InsertItemTemplate>
              </asp:TemplateField>

            <asp:BoundField DataField="name" HeaderText="name"/>
            <asp:BoundField DataField="phone" HeaderText="phone"/>
            <asp:BoundField DataField="site" HeaderText="site"/>

            <asp:TemplateField HeaderText="segment">
                  <InsertItemTemplate>
                      <asp:DropDownList ID="ddlSegment" runat="server" DataSourceID="ShopSegmentDataSource" DataTextField="segment"
                       DataValueField="segment" SelectedValue='<%# Bind("segment") %>' ></asp:DropDownList>
                  </InsertItemTemplate>
              </asp:TemplateField>


               <asp:TemplateField HeaderText="image">
                  <InsertItemTemplate>
                     <asp:FileUpload ID="FileUpload1" runat="server" />
                  </InsertItemTemplate>
              </asp:TemplateField>

          <asp:commandfield ButtonType="Image" showinsertbutton="true" InsertImageUrl="buttons/new.png" ShowCancelButton="false" showheader="true" headertext="???? ????" />
        </fields>
      </asp:detailsview>
   <%--details view--%>


AppCode/ShopLogic.cs:
public void InsertNewShop(string title, string name, string phone, string site, string segment, object FileUpload)
    {
        FileUpload FileUpload1 = FileUpload as FileUpload;
        //upload picture
        string imagePath = "~/ShopsImages/" + DateTime.Now.ToString("ddmmyy_hhmmss") + FileUpload1.FileName;
        string fullPath = HostingEnvironment.MapPath(imagePath);
        FileUpload1.SaveAs(fullPath);


        //create shop object
        shop newShop = new shop();
        newShop.title = title;
        //...more code...
        db.AddToshops(newShop);
        db.SaveChanges();
    }