The Locking tab is only visible to you if you are blocked. Blocks can have various reasons, e.g:

• Missing documents that you still need to submit, e.g. the certificate of de-registration from your previous university,
• problems with your health insurance company (missing insurance confirmation or late payment of your health insurance contributions) or
• a final failed examination.

A block prevents you from re-registering for the next semester, i.e. even if you have transferred the semester fee, you will not be re-registered for the next semester.
Take action and make sure that the causes of the blocks are eliminated, e.g. by submitting documents or contacting your health insurance company.

If you have any questions about the restrictions, please contact the Registrar's Office.