Dropdownlist数据绑定不上解决方法

Dropdownlist数据绑定不上
DAL层是这样写的

C# code

public DataSet GetList(string strWhere)        {            StringBuilder strSql = new StringBuilder();            strSql.Append("select NewsTypeID,NewsType ");            strSql.Append(" FROM Accounts_NewsType ");            if (strWhere.Trim() != "")            {                strSql.Append(" where " + strWhere);            }            return SQLHelper.Query(strSql.ToString());        }

C# code

public DataSet GetList(string strWhere)        {            return dal.GetList(strWhere);        }public DataSet GetAllList()        {            return GetList("");        }

C# code

private void BindNewsType()    {        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();    }