Why @User.IsInRole not working?

I installed Dotconnect PostgreSql with folowing this tutorial http://ift.tt/1h8NCef All works fine, but when I call Admin role from View.cshtml with this operation : @(User.IsInRole("admin")) { } , after that showing error as

"Operation is not Supported"

But Rolemanager was enabled in web.config

Showing Exception that :

An exception of type 'System.InvalidOperationException' occurred in Devart.Data.PostgreSql.Web.dll but was not handled in user code

Additional information: Operation is not supported

Code:

<roleManager defaultProvider="PgSqlExtendedRoleProvider" enabled="true" cacheRolesInCookie="true" cookieName=".ASPROLES" cookieTimeout="30" cookiePath="/" cookieProtection="All">
  <providers>
    <add name="PgSqlExtendedRoleProvider" type="Devart.Data.PostgreSql.Web.Providers.PgSqlExtendedRoleProvider, Devart.Data.PostgreSql.Web, Version=7.3.457.5, Culture=neutral, PublicKeyToken=09af7300eec23701" description="dotConnect for PostgreSQL extended role provider" connectionStringName="DefaultConnection"/>
  </providers>
</roleManager>

Quick watch showing : false.
Why is this function throwing an exception? How can I fix it ?

via Chebli Mohamed