Whilst deploying Lync Enterprise Edition with 3 Front End Servers I cam across an interesting issue. FE 1 was fine but when I fired up FE 2 and got to the certificate wizard the OAuth Certificate was missing.
Checking the Cert Manager through MMC shows that the cert isn't in the personal store. Adding it there manually didn't help me much either...
Retracing my steps I noticed that the internal DNS records had not been added yet.
You must add the Front End Pool FQDN with all the individual Front End Server IP addresses. Ensure that when you run nslookup that all the Front End IP's are found. If an IP is missing from DNS you wont get the OAuth Certificate....
Object reference not set to an instance of an object.