登录页面无法登录到相应页面

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
   

   
    protected void Button1_Click(object sender, EventArgs e)
    {
        string str = ConfigurationSettings.AppSettings["dsn"];
        SqlConnection cn = new SqlConnection(str);
        cn.Open();
        string mysql = "select * from admin where aid='" + tbx_aid.Text + " 'and apassword ='" + tbx_apassword.Text + "'";
        SqlCommand cm =new SqlCommand(mysql,cn);
        SqlDataReader ur =cm.ExecuteReader();
        if (ur.Read())
        {
        label4.Text = "";
        Session["aid"]= ur["aid"];
        Session["aname"]= ur ["aname"];
        Session["apower"]= ur ["apower"];
        Session["adep"]= ur ["adep"];
        if (Session["apower"]=="1")
        {

            Response.Redirect("admin.aspx");
        }
         if (Session["apower"]=="2")
        {
            Response.Redirect("kqmanage.aspx");
        }
         if (Session["apower"]=="3")
        {
            Response.Redirect("lr3.aspx");
        }
        label4.Text = "用户名/密码不正确，请重新输入";
         
     } cn.Close();
}
}
我运行了一下没有报错，可就是输入用户名和密码以后无法登录相应的页面