auto-enter calculation field

[new comer]

I have a FM7 db import records from a txt file. in the DB file, there is an auto-enter calculation field (field_B)defined as:

Case(not IsEmpty(field_A); "postive"; "negative")

where "field_A" is a simple imported text field

but even if field_A is not empty, field_B still show "negative".

Anybody know why is that? Thanks in advance!

[new comer]

Got the answer form a Queue's old post! I need uncheck the 'Do not replace existing value for field (if any)' option. Thanks Queue!