Business rules using Additional fields

Hi,

I have problem with Business Rules which I set condition with Request - Additional Fields.

I created a request additional field (pick list type), called Supplier. Then, I created this business rule:

Execute
: when a request is created and edited.
Criteria: Supplier is "Supplier1"
Action: Change Status to "Onhold".

When I create a new request with Supplier = "Supplier1", the rule works fine. But when I set Supplier field to "Supplier1" in a existing request, rule not works. I need another update (any type of update..) to fire the rule: it seems like the application evaluates the initial values of criteria fields, and not the final ones.

This happens only with Request Additional fields. With standard fields, the rule works fine.

Any idea to solve this problem?

Thanks,
sl