protected void btnDeleteImage_Click(object sender, EventArgs e)
        {
            //get id number
            Button btnDeleteImage   = (Button)sender;
            Int16  portfolioImageId = Convert.ToInt16(btnDeleteImage.CommandArgument);

            DeletePortfolioImage(SelectedPortfolioCategory.GetPortfolioImageById(portfolioImageId));

            //reload
            BindCategory();
        }