I had a similar issue. A couple of things to check, make sure your claims to windows token service is running in sharepoint.
Also, did you update the c2wtshost.exe.config?
\Program Files\Windows Identity Foundation\v3.5\c2wtshost.exe.config
The following is an example of the configuration file:
By default no callers are allowed to use the Windows Identity Foundation Claims To NT Token Service.
Add the identities you wish to allow below.
<add value="WSS_WPG" />