How to get dropdownlist selected value while I am editing data in detailsView control?

I have one dataAccessLayer.cs which supply edit, delete, update method; one GridView control to show limited data; one DetailsView control to show more details value. When i press select button in gridview and then detailsView fill detail value. But I create dropdownlist on the codeBehind to show data in detailsView. so far there are no bug but When I want to edit data in detailView program do not catch dropdownlist value for editing

protected void DetailsView1_DataBound(object sender, EventArgs e)
    {
        if (DetailsView1.CurrentMode == DetailsViewMode.Edit)
        {
            DropDownList dropDownList = (DropDownList)DetailsView1.FindControl("DropDownList2");
            dropDownList.DataSource = ss.DataTableMtd("spGetAllMarkaIdName");
            dropDownList.DataTextField = "Marka_Name";
            dropDownList.DataValueField = "Marka_Name";
            dropDownList.DataBind();
        }
    }

At last I find the answer.

    protected void DetailsView1_ItemUpdating(object sender, DetailsViewUpdateEventArgs e)
    {
        ObjectDataSource2.UpdateParameters["MarkaName"].DefaultValue = 
        ((DropDownList)DetailsView1.FindControl("DropDownList2")).SelectedValue;            
    }