Hi. I am trying to append all excel files in a single folder into one big file, but the code below throws the r(601) error. I've made sure that the files have no leading or trailing spaces, so am not sure what is happening. Any help would be great. Thanks.

Code:
local filenames: dir "C:\Users\katja\Dropbox\Raw Data"  files "*.xlsx*"

foreach f of local filenames {
import excel using `"`f'"'
gen source = `"`f'"'
display `"Appending `f'"'
append using `building'
save `"`building'"', replace
}

export excel using 1_large_excel_file.xlsx, replace