CrystalReports XI RDC causes a disfunction of Lotus Notes Single SignOn

Our customer uses Lotus Notes. When he installed the CR RDC merge modul (XI Rel. II, SP6), the single signon for Lotus Notes doesn't work anymore. That means the customer has to type in username and password once more if he want's to use Lotus Notes. It seams that the single signon service is running.

The registry key "ProviderOrder"="RDPNP,LanmanWorkstation,WebClient,npnotes" is correctly sorted (I found that in another forum). Any suggestions? TIA, F. Bartsch