problem in custom change password

See more:

C#

ASP.NET

membership

hi to all,

i use asp membership,
now i want create a page for user for change password,but i don't want to use <asp:ChangePassword>
i want create this custom,
my problem is: i want check user oldpassword from oldpassword textbox ,if currect, password change, and display "success" message, or wrong, display "oldpassword wrong" message.

my html code is:

my problem is: i want check user oldpassword from oldpassword textbox ,if currect, password change, and display "success" message, or wrong, display "oldpassword wrong" message.

and my c# code is:

protected void submitchangepassword_Click(object sender, EventArgs e)
       {
           try
           {
               System.Web.Security.MembershipUser usr = System.Web.Security.Membership.GetUser();
               usr.ChangePassword(oldpassword.Text, newpassword.Text);
               errorlabel.Text = "Success";
           }
           catch (Exception ex) { errorlabel.Text = ex.ToString(); }
       }

thank's for you'r help