在当使用条件的上下文(在 'Admin' 附近)中指定了非布尔类型的表达式

using System;
using System.Data;
using System.Text;
using System.Data.SqlClient;
using DBUtility;//Please add references
namespace DAL
{
                  /// <summary>
        ///     根据用户名获取用户ID
        /// </summary>
        public DataSet GetSessonUserID(string UserName)
        {
            StringBuilder strsql = new StringBuilder();
            strsql.Append("select UserID  ");
            strsql.Append("from Accounts_Users ");
           
            if (UserName!="")
            {
                strsql.Append("where " + UserName);
            }
            return SQLHelper.Query(strsql.ToString());
        }
        /// <summary>
        ///     根据用户名获取用户类别ID（RoleID）
        /// </summary>
        public DataSet GetSessionRoleID(string UserName)
        {
            StringBuilder strsql = new StringBuilder();
            strsql.Append("select RoleID ");
            strsql.Append("from Accounts_Users ");
            if (UserName.Trim()!="")
            {
                strsql.Append("where " + UserName);
            }
            return SQLHelper.Query(strsql.ToString());
        }
        /// <summary>
        /// 获得数据列表
        /// </summary>
        public DataSet GetList(string strWhere)
        {
            StringBuilder strSql = new StringBuilder();
            strSql.Append("select UserID,UserName,UserPassWord,TrueName,Sex,Age,BirthDay,Phone,Email,EmployeeID,DepartmentID,UserType ");
            strSql.Append(" FROM Accounts_Users ");
            if (strWhere.Trim() != "")
            {
                strSql.Append(" where " + strWhere);
            }
            return SQLHelper.Query(strSql.ToString());
        }
           

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using DBUtility;
using Model;
using DAL;
using BLL;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;

public partial class Admin_AddNews : System.Web.UI.UserControl
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (Session["UserName"] == null)
        {
            Response.Write("<script>alert('您还没有登录！')</script>");
            Response.Redirect("/Admin/Login.aspx");
        }
        if (!IsPostBack)
        {
            BindNewsTypeBind();
        }
        
    }
    private void BindNewsTypeBind()
    {
        BLL.Accounts_NewsType bll = new BLL.Accounts_NewsType();

        DataSet ds = bll.GetAllList();
        this.NewsType.DataSource = ds.Tables[0];
        this.NewsType.DataTextField = "NewsType";
        this.NewsType.DataValueField = "NewsTypeID";
        this.NewsType.DataBind();

    }
    protected void NewsType_SelectedIndexChanged(object sender, EventArgs e)
    {
        BLL.Accounts_NewsType bll = new BLL.Accounts_NewsType();
        DataSet ds = bll.GetList(NewsType.SelectedItem.Value);
        if (ds.Tables[0].Rows.Count>0)
        {
            this.NewsType.DataSource = ds;
            this.NewsType.DataTextField = "NewsType";
            this.NewsType.DataValueField = "NewsTypeID";
            this.NewsType.DataBind();
        }
        //string NewsTypeID = NewsType.SelectedValue;
        //BindNewsTypeBind();
    }

    protected void SaveBtn_Click(object sender, EventArgs e)
    {
        BLL.Accounts_Users UsersBll = new BLL.Accounts_Users();
        BLL.Accounts_News bll = new BLL.Accounts_News();
        ImageUpLoad.SaveAs(Server.MapPath("../ImageUpLoad/"+ImageUpLoad.FileName));
        try
        {
            if (TitleText.Text.Trim() == "" && ImageUpLoad.FileName != "" && CKEditorControl1.Text != "")
            {
                Response.Write("<script>alert('请输入新闻标题！')</script>");
            }
            else if (TitleText.Text.Trim() != "" && ImageUpLoad.FileName == "" && CKEditorControl1.Text != "")
            {
                Response.Write("<script>alert('请选择一张图片作为标题图片！')</script>");
            }
            else if (TitleText.Text.Trim() != "" && ImageUpLoad.FileName != "" && CKEditorControl1.Text == "")
            {
                Response.Write("<script>alert('请输入新闻内容！')</script>");
            }
            else if (TitleText.Text.Trim() == "" && ImageUpLoad.FileName == "" && CKEditorControl1.Text == "")
            {
                Response.Write("<script>alert('请填写您要发表的新闻标题、标题图片、新闻内容，并且选择对应的新闻类别！')</script>");
            }
            else if (TitleText.Text.Trim() != "" && ImageUpLoad.FileName != "" && CKEditorControl1.Text != "")
            {
                Model.Accounts_News model = new Model.Accounts_News();
                model.NewsTitle = TitleText.Text;
                model.NewsPicture = "../ImageUpLoad/" + ImageUpLoad.FileName;
                model.NewsTypeID = Convert.ToInt32(NewsType.SelectedItem.Value);
                model.NewsText = CKEditorControl1.Text;
                model.NewsDateTime = DateTime.Now;
                model.UserID = Convert.ToInt32(UsersBll.GetSessonUserID((string)Session["UserName"]));//从Session中获取当前登录用户的用户名
                model.RoleID = Convert.ToInt32(UsersBll.GetSessionRoleID((string)Session["Description"]));//从Session中获取当前登录用户的组
                bll.Add(model);
                Response.Write("<script>alert('发布成功！')</script>");
            }
        }
        catch (Exception ex)
        {

            Response.Write("错误："+ex);
        }
       
        
        
        
    }
}