Access denied by "Granular Backup"

Question

When I try to copy a custom list from one of subsites of my weapplication's site collection to another by:

• Central Administration --> Backup and Restore --> Export a site or list --> Filling Options --> Start Export

I am getting:

• Access to the path '\\sptest\TstShare' is denied

I also tried to export a list to local drive having gotten:

• Access to the path 'c:\CustomerParam.cmp' is denied

I am site collection administrator. Though I am accessing the testing machine over internet using RDP.
I have no problem to access \sptest\TstShare from Windows Explorer or other apps. I am (i.e. domain user) explictly added in permissions of this share with FULL permissions on it to domain user under which I work.

So, what is the problem?

UPDATE
I am in (local) Administrators group.
My farm administrators recently:

• 1) removed me from site collection administrators but I put me back there
• 2) disabled local Administrator and Guest accounts so my testing machine with SP 2010 Server (and all the rest) does not have any local accounts.

This testing machine is really virtual machine ti which I connect over internet by RDP.

Now my domain account under which I develop is the site collection owner/administrator, makes part of 2 local groups:

• 1)Administrators
  Description:
  Administrators have complete and unrestricted access to the computer/domain
• 2)WSS_ADMIN_WPG
  Description:
  Members of this group have write access to system resources used by Microsoft SharePoint Foundation
  Members:
  • BUILTIN\Administrators (S-1-5-32-544)
  • my domain acc
  • sp farm services domain acc
  • et al

I found tha article

• "Plan for security roles (Windows SharePoint Services)"
  http://technet.microsoft.com/en-us/library/cc288186%28v=office.12%29.aspx

very helpful as it contains comparison of farm Administrator, Administrators groups and site collection administrators.

So, my collateral question:
Should I enable local Administrator account back?
Does it needed to develop in Sharepoint 2010 (Enterprise, Server)?

Update 2:
The domain of (domain) user which I use is not the same as domain of dev (VM) machine with Sharepoint server which I use. Though I didn't dig into domains configuration since I see it from virtual machine (and this is not my concern).

Update 3:
"BUILTIN\Administratos" group is part of "Farm Administrators" but my username in this group gives "404 FILE NOT FOUND"

Answer 1

Please check the information in the technet http://technet.microsoft.com/en-us/library/ff468694.aspx

This will explain the permission that needs to be set. In your case make sure that the OWS Timer account have access to the share. Backup using c:\somefolder will always fail because the backup job execute a stored procedure on the database server and this stored procedure needs a UNC to process.