Filemanager 3 and computed fields

I have FM3 version 5.3 using Clarion 10.
In the previous version of a file, I added a computed field that returns the three first characters of another field. I used ForceSqlDataType = AS (substring([Plass],(1),(3))) This worked fine for adding the field.
Now I added another field and I get FM3 error [FM3] 37000: Incorrect syntax near the keyword ‘as’.
The new field is added OK, but errormessages are anoying…
I can drop the field before update, so the field is recreated each time, but is there a better way?