Issue in Authentication using AD Group

Hi All,

I am facing a strange issue in Authentication using an AD group.

We have configured  Active Directory group Authentication on one of our portal  such that,  users only in a particular AD group will be able to access the portal.

The authentication scenario is working fine on the development site, but authentication fails on the stage  & Production site.

Users in that group are not able to access the stage & production portal.

The AD group name is configured in the respective Web.Config  for the sites , with the exact entry  as follows :

<authorization>

<allow roles="Domain\GroupName"/> 

 <deny users="*" />        

</authorization>

Same issue comes up if we try accessing the group using code,  it works on the Dev site but not on stage & production:

GlobalFilters.Filters.Add(new System.Web.Mvc.AuthorizeAttribute() { Roles = System.Web.Configuration.WebConfigurationManager.AppSettings["LDAPAuthorizeRole"] });

Web.config entry

<add key="LDAPAuthorizeRole" value="Domain\GroupName" />

Can someone help on this , to pin point the exact reason why such a strange issue is coming up.

Thanks &  Regards

gc_new