Last Updated on 2012-06-11.
By default, it is only possible to export a Hyper-V virtual machine on a local hard drive.
If you want to be able to export to a network share which is created on another machine, you have to add the computer name of the Hyper-V host to the security settings of the other machine with the share (full access).
This should fix this error.
If not, try (for testing purposes) to add user SYSTEM, or everybody with full write access to the share.