I have a folder containing some 70,000 systematically named files which I am going to merge into fewer files eventually. I start with running a simple loop using the capture confirm file construct to check which files do not exist but I always receive code 601 (not found) even for the files I can see that exist. Can anyone think of a reason why this happens?

foreach t in 17928 17956 17987 18017{
foreach f in 5560003468 5560004615 5560005331 {
capture confirm file "C:\Users\Nima\Desktop\Directors\Merged`t'-`f'"
dis _rc
use "C:\Users\Nima\Desktop\Directors\Merged`t'-`f'"
clear
}
}

Just to illustrate the problem, I have added a shortened version of the loop I am running above. All 12 files do exist above and Stata opens them one by one in the loop but first displays code 601.