::
Have you just registered/received your candidate ID? If that’s the case it might take 2-3 days for scheduling to become available.
From the Prometric FAQ:
How long will it take for my eligibility or authorization to test to be downloaded into the system so that I can schedule an appointment to test?
Please note that not all test sponsors require eligibility, therefore, you may be able to test immediately. For those programs requiring eligibility, the files are downloaded and test appointment scheduling is available within 48-72 hours of receiving authorization from the test sponsor.