cacheRolesInCookie not caching roles

Question

Hi all, I am trying to use forms authentication with the following configuration settings. I have set cacheRolesInCookie to true. However, I am finding that the RoleProvider's GetRolesForUser method is called on every request. I can see that the cookie .asproles is created and has data in it but it appears to be ignored.

Has anyone come across this problem before? Any help would be much appreciated.

    <authentication mode="Forms">
  <forms
   name=".formsauth"
   loginUrl="~/Login.aspx"
   defaultUrl="~/Home.aspx"
   slidingExpiration="true"
   timeout="20"
   path="/" 
    />
 </authentication>

 <!-- Membership Provider -->
 <membership defaultProvider="CustomMembersipProvider">
  <providers>
   <add name="CustomMembersipProvider"
     type="Company.Membership.CustomMembersipProvider" />
  </providers>
 </membership>

 <!-- Role Provider -->
 <roleManager defaultProvider="CustomMembershipRoleProvider"
   enabled="true"
   cacheRolesInCookie="true"
   cookieName=".asproles"
   cookieTimeout="20"
   cookieSlidingExpiration="true"
   cookieProtection="All" createPersistentCookie="true">
  <providers>
   <add name="CustomMembershipRoleProvider"
     type="Company.Membership.Provider.CustomMembershipRoleProvider" />
  </providers>
 </roleManager>

Many thanks Naren