Shadow copy of .ost file

Question

I use .ost file and try to create shadow copy for 2 files:

• \?\GLOBALROOT\Device\HarddiskVolumeShadowCopy22\Users\Admin\AppData\Local\Microsoft\Outlook\[email protected]
• \?\GLOBALROOT\Device\HarddiskVolumeShadowCopy22\Users\Admin\AppData\Local\Microsoft\Outlook\test.txt

But when I call:

File.Exists(shadowFilePath)

I get false for [email protected] and I get true for test.txt file. How can I create shadow copy of .ost file when I use outlook ?