after reading the virtualbox forums especially
https://forums.virtualbox.org/viewtopic.php?f=7&t=78840#p368748 it is clear that the problem is on the virtualbox side Virtualbox 5.1 exports cannot be direclty mported in 5.0
after reading the virtualbox forums especially
https://forums.virtualbox.org/viewtopic.php?f=7&t=78840#p368748 it is clear that the problem is on the virtualbox side Virtualbox 5.1 exports cannot be direclty mported in 5.0