Can't transfer my World to my Realm

When I try to move my world to my Realm it does the export but then gives an error saying "an error has occurred" while initializing upload, sometimes after a few minutes. I really want to use realms to play with friends but if I can't move my world to the realm then I don't think I would continue with realms as I don't want to start a brand new world.

 

Please help me get my world transfered to my Realm.

 

Thank you!