You have probably already exceeded the maximum loan period (in which case the books must be brought to the library) or the work has been reserved by another user. Alternatively, you may have an expired registration (the system will block the possibility of renewal if there is less than one month left until the end of the registration validity period) or an unpaid fee. Check your account status, any fees can be also paid online. You can also register renew online - then the renewal option will be unlocked again.
If another reader is not interested in the book, you can extend its loan. In total, you can have the book on loan for up to 3 months if no other reservation is placed for it.
