Folder not found error on sharing contacts

We are in an Exchange environment, same domain, same site.

I tried to share a Contacts folder from a user on Outlook 2010 to a user on Outlook 2013 using the instructions at http://office.microsoft.com/en-us/outlook-help/share-a-contacts-folder-with-others-HA010355056.aspx.

Everything seemed to go OK. Recipient got the sharing email, but when she clicked on“Open this contacts folder” she got the error message "The folder you selected is not available".

We tested sharing using 2 people using Outlook 2013 and it worked perfectly. Suggestions?

Mike