In most cases this is because you are not linked with your trust.
Your training lead is required to invite you to the trust once you have created an account. This will ensure that all the correct trainees/trainers appear in the dropdown boxes when completing DOPs/DOPyS/feedback etc.
If your training lead is unsure how to invite you to the trust please forward them to the following FAQ: How to invite trainees to the trust.
Your work address is needed to be able to book a course. This populates automatically once you are linked to the trust and cannot be populated otherwise.