I got the above error that points to file4 which has two columns. Not sure if the error is misleading me. The program is working until this point where I add the few lines of codes to filter file4 and assign the value. Thanks.
file1.xlsx (9.5 KB)file2.xlsx (776.2 KB)
file3.xlsx (82.5 KB)
file4.xlsx (80.1 KB)
test-filter.xaml (45.4 KB)