Reconnect disabled archive mailbox

Hi

Im trying to reconnect a disabled archive mailbox. Im following this guide http://technet.microsoft.com/en-us/library/jj651146(v=exchg.150).aspx

but when running the command "connect-mailbox ...." i get the following error:

WARNING: An unexpected error has occurred and a Watson dump is being generated: Object reference not set to an instance
 of an object.
Object reference not set to an instance of an object.
    + CategoryInfo          : NotSpecified: (:) [Connect-Mailbox], NullReferenceException
    + FullyQualifiedErrorId : System.NullReferenceException,Microsoft.Exchange.Management.MapiTasks.ConnectMailbox
    + PSComputerName        : serverx.contoso.local

Not sure why i get this

Thanks for the help

/Carlos