Hernan,
Can't you use FULLPATH() inside of VFP? GetFullPathName() doesn't do any lookups it just does basically:
SYS(5) + CURDIR() + lcFileName
FULLPATH() does the same thing except it DOES search along the Fox path to try and find the file. If you only want GetFullPathName() functionality then using the code above is easier and doesn't require API calls.
The other caveat is that FULLPATH() may return a string if the file doesn't exist so you may have to double check with FILE() after FULLPATH has returned.
+++ Rick ---