The Active Directory Membership Provider has not been initialized.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.InvalidOperationException: The Active Directory Membership Provider has not been initialized.

Source Error:

Line 27: void Login1_Authenticate(object sender, AuthenticateEventArgs e)
Line 28: {
Line 29: e.Authenticated = UserManager.Default.ValidateUser(this.Login1.UserName, this.Login1.Password);
Line 30: }
Line 31:

<roleManager enabled="true" cacheRolesInCookie="true" defaultProvider="Sitefinity">
<providers>
<clear/>
<add name = "Sitefinity"
    connectionStringName = "ActiveDirectory" 
    connectionUsername="ar\SitefinityService"
    connectionPassword="somePassword"
    groupMaps = "SitefinityAdmin"
    type = "Telerik.Security.ActiveDirectory.TelerikADRoleProvider, Telerik.Security"
/>

<add connectionStringName="DefaultConnection" applicationName="/" name="Public"      type="Telerik.DataAccess.AspnetProviders.TelerikRoleProvider, Telerik.DataAccess"/>

</providers>
</roleManager>

<membership defaultProvider="Sitefinity" userIsOnlineTimeWindow="15" hashAlgorithmType="">
<providers>
<clear/>
<add connectionStringName="ActiveDirectory"
    enableSearchMethods="true"
    attributeMapUsername="sAMAccountName" 
    connectionUsername="ar\SitefinityService"
    connectionPassword="somePassword"
    name="Sitefinity"
    type="Telerik.Security.ActiveDirectory.TelerikADMembershipProvider, Telerik.Security" />

<add name="Public" connectionStringName="DefaultConnection"     type="Telerik.DataAccess.AspnetProviders.TelerikMembershipProvider, Telerik.DataAccess" enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" applicationName="/" requiresUniqueEmail="false" passwordFormat="Hashed" maxInvalidPasswordAttempts="5" passwordAttemptWindow="10" passwordStrengthRegularExpression="" minRequiredPasswordLength="1" minRequiredNonalphanumericCharacters="0"/>
</providers>
</membership>