Error Validating Agvance File

Q.  Why do I get the following error message while restoring a database? 

Error validating Agvance file. RESTOREHEADERONLY is terminating abnormally. Cannot open backup device 'x:\xxxxxx\xxx.dat'. Operating system error 3(The system cannot find the path specified).

A.  This happened because the correct path to the file has been entered but it is not using the UNC path. In other words, instead of using a drive letter, try using \\servername\sharename\ in front.