Problem with modifying dta files from directory I get the error: no variables defined

Hi, I´m working with a code to call up files from a directory and save them in another folder with changes.
I have dta files for each quarter (years 2005-2018) and want to save them with a few changes before doing appending them.

Code:

    
foreach y in 05 06 07 08 09 10 11 12 13 14 15 16 17 18 {
    forval q=1/4 {
        capture use "$od\sdemt`q'`y'.dta", clear
                destring n_ent, replace
        capture gen year=20`y'
        capture gen quarter=`q'
        save "$prd\sdemt`q'`y'.dta", replace    
        }
}

Problem: when I run the code it gets me the error:

no variables defined.

I am working in a Windows 10 computer, however, when I run this code in a mac computer it works perfectly.
I made sure that the folder is the one with the dta files using the command

Code:

cd

Also changed / for \ while using Windows 10.
Does anyone have any advice of what could be happening?
Thank you!

Eugenia