DropDownList ddlWorkTypeTitle = (DropDownList)dlsviewEmployee.FindControl("ddlWorkTypeTitle");
  this.dbForEmployee = new DataBaseForEmployee();
  ddlWorkTypeTitle.DataSource = this.dbForEmployee.GetEmpWorkTypeDt();   
  ddlWorkTypeTitle.DataTextField = "WorkTypeTitle";
  ddlWorkTypeTitle.DataValueField = "WorkTypeNum";
  ddlWorkTypeTitle.DataBind();

ddlWorkTypeTitle.Item.Count不为0，但是页面上的DropDownList不显示数据