xcopy unc file not found

I am attempting to execute xcopy command that copies a file from one UNC path to another but I keep getting file not found error. Using windows file explorer I know the path is correct and the file name exists but the error persists. What gives?

C:\Windows\System32\xcopy.exe "\\MySourceShare\MyFolder1\MyFolder2\MyFolder3\MyF开发者_高级运维older4\MyFolder5\filename" "\\MyDestShare\MyFolder1\filename" /Y

Thanks

This now works after a lot of permission debugging. For the record you CAN copy files using UNC.

When I had this problem only way to solve it was to use IP addres instead of machine name in the UNC path