I believe you will need to set up the default service for that calendar application.
To do this from your applications screen select the options icon. Then from the options lists select advanced options. From the advanced options list select default services.
The very first selection is the calendar entry. Select which email account you wish to make the default entry.
Make sure both the calendar on outlook and on your phone have the same email address... and I think there is something in the conflict reports from DM make sure in your sync options that you dont have it set to auto resolve I had that trouble too.. as well what OS is on your PC?