how to login in fba enabled SharePoint site when i use passwordFormat="Encrypted" in my web.config file.

using below code i am not able to login page. how i can validate user when i am using passwordFormat="Encrypted"

if (SPClaimsUtility.AuthenticateFormsUser(ctxUri, txtUserName.Value.Trim(), encodedPassword))
                {
                    string strDirectLink = "/Pages/Home.aspx";
                    SPUtility.Redirect(strDirectLink.ToString(), SPRedirectFlags.Trusted, HttpContext.Current);
                }
                else
                {
                    lblErrMsg.Text = "Invalid username. Please try again";
                }

always code execute in else part and show "Invalid username. Please try again" message.

my CA+WP+STS web.config files

<add name="FBAMembership" type="System.Web.Security.SqlMembershipProvider, System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" applicationName="/" connectionStringName="AspNetSqlProvider" enablePasswordReset="true" enablePasswordRetrieval="true" passwordFormat="Encrypted" requiresQuestionAndAnswer="false" requiresUniqueEmail="false" />

Sreekanth