External Harddrive serious Tag Problem

Dear Pioneer Team,

My collection is on an SSD Harddrive to work and change tags and Playlists on every PC that is arround. 

This week I worked (at work) hard on a playlist, changed colors, added comments, changed key to camelot etc... 

After pluging in the external database to my residential computer at home, all changes where gone. 

WHat happened?

How can I avoid that?

Thank you.