WCF and ASP.Net Membership, Roles and Profile

Hi,
I have a client asp.net website that uses  ASP.Net Membership, Roles and Profile providers and Login controls.
I need to expand the application so was going to use WCF Workflows, the ASP.Net website will be hosted on a different server than the WCF Services so what I want to do is get the ASP.Net Website to auth via the WCF Service.
So process will go:
ASP.Net Website ------------------> WCF Service ------------------> SQL Database (Membership, Roles, Profile, Workflow Persistence Data and Business Data)
I tried creating a custom Membership and Role providers but I have had problems managing the users (Membershipuser class) saying null when a vaild user has been return by the WCF Service as can access the properies but not the methods.
Am I doing this the right way or is there other built in classes that I have missed?
Thanks.
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