Create check constraints in a Interbase data model

[cazita]

Hi,
I have a class with Stereotype  = "table" and Database = "Interbase". In this class i created an attribute "Flag_Check_List" with Data Type = "char" and an operation with stereotype = "check" and Initial Code = "Flag_Check_List in ('S', 'N')". Otherwise when I generate SQL script (menu Project -> Database Engineering -> Generate Package DDL) the check constraint is incorrect. The script generated for check constraint is:

ALTER TABLE PRODUCT
      ADD CONSTRAINT CK_PRODUCT_1 CHECK ()
;

Someone know why Initial Code is not in SQL script?