InfoPath Dev

I am able to submit data to database with no problem.
And I can also pull data back by query.
Everything works fine at this point.

Here is the problem:
After I make changes in the fields, the submit button is disable.
I cannot submit data back to database.

1. I am sure that my main connection is "retrieve & submit."
2. I am sure that the ruls that I set are all qualified.

Please advice and thanks in advance.

This seems a little weird but maybe it is happening because you are using an InfoPath generated Submit button and there is some extra hidden logic behind that. Try removing the submit button you currently have, adding a new one, and this time use Rules and Custom Code and a rule on the button to do the submission. I think this will fix the issue.