New-PublicFolderMigrationRequest - Couldnt connect to the source mailbox

Hi All,

When performing the new-publicfoldermigrationrequest command on exchange 2013 server I receive the following error:

Couldn't connect to the source mailbox.
    + CategoryInfo          : NotSpecified: (:) [New-PublicFolderMigrationRequest], RemoteTransientException
    + FullyQualifiedErrorId : 19495301,Microsoft.Exchange.Management.RecipientTasks.NewPublicFolderMigrationRequest
    + PSComputerName        : svr12365.bcb.local

I am copying from Exchange 2007 on sbs2008 server. if I run get-publicfolderdatabase from exchange 2013 powershell it returns with the correct database name and server.

any ideas?

Many Thanks