Got "RPC server is unavailable" error when configuring user profile disk to use a samba share

I mostly followed this guide (http://blogs.msdn.com/b/rds/archive/2012/11/13/easier-user-data-management-with-user-profile-disks-in-windows-server-2012.aspx). The file server is samba based.

I've verified below two cases:

1. I could map the share to a local drive from windows and create/modify files/folders without problem.

2. I could set the disk path to a windows share.

PS C:\Users\Administrator.000> Set-RDSessionCollectionConfiguration -CollectionName "Test Session Collection" -EnableUserProfileDisk -MaxUserProfileDiskSizeGB 20 -DiskPath \\remote-file-server\data2

Could not create the template VHD. 
Error Message: The RPC server is unavailable. (Exception from HRESULT: 0x800706BA).    + CategoryInfo          : InvalidResult: (:) [], WorkflowTerminatedException    + FullyQualifiedErrorId : JobStateFailed    + PSComputerName        : localhost