Sharing between institutions is difficult, in part because discussions eventually boil down to the need for someone to sign something!  That person needs to move from ‘Yes, that sounds good’ to, ‘Yes I have the authority to grant these rights on behalf of the institution, and I am willing to do so in writing.’  Even those responsible for copyright and IPR in an institution may hesitate, and sometimes for good reasons.  The generally accepted institutional policy may not be written down, or the individual who has the right to grant permissions may not have been clearly and formally identified.  In such cases, it often takes someone who is in tune enough with the culture and history of the organisation, and who feels confident to make an assertion on the institution’s behalf who will ultimately be ‘ready to sign’.  Such people can be hard to find!