Possible error in online documentation

[shilton]

I believe there may be a documentation error.

on page:

help.appsheet.com

List Expressions and Aggregates

List expressions use operators that result in a list or numeric value.

Under Heading:
" Preventing Duplicate Field Values"
Code:
NOT(IN([_THIS], SELECT(Customers[State], NOT(IN([CustomerId], LIST([_THISROW].[CustomerId]))))))

I could not get the above to work. In fact when I tried to hit SAVE, it looked like it was synching but did not actually save anything and the SAVE button remained blue. No errors or warning. This problem is mentioned in the community as sometimes occuring.

I managed to get the desired result by the below code…which is also shorter, so even better!
NOT(IN([_THIS], SELECT(Customers[State],TRUE)))