For sake of readability, I’m adding line numbers and indentations to your code. It won’t run like this - I’m just doing it for demonstration purposes.
1 IF(
2 {TRACKING},
3 IF(
4 LEN({TRACKING})= 12,
5 “https://www.fedex.com/apps/fedextrack/”
6 )&{TRACKING}
7 )
Without knowing what the error message is, my best guess is that your error is occurring on line 6. I believe &{Tracking} should be inside of the parenthesis.
