[Koha] Not Reservable

I am a new user of KOHA looking for help. I have installed KOHA version 2.2.7 on our network using Linux as the OS. However, the bibliographic details of my records do not show when I search for items via the catalog. The message written against each of the blank items reads 'Not Reservable'. I am sure the database is there because I am able to see them in the Reservoir. How can I get to KOHA's active table? What could be the problem? Thanks Beatrice