InfoPath Dev

Hi, I am having extreme difficulty in making my workflow work.  I am creating a workflow that will grab an email address from a text box field in an infopath form and use that email address to assign a to do item. I can make the workflow work the first time.  My difficulty is after it works the first time, and the user opens the form again and inputs a new email address, saves, and closes it does not send the task.  For better understanding here are my sequence of events.

1. User creates form and inputs email address into text box field at the bottom of the form

2. User clicks submit button

3.  A task is assigned to the email address provided by the user.

4.  Individual recieves the task in an email, opens the link reviews the form, signs, and saves the form.

5.  User who created the form, then opens the form again sees the signature and inputs a new email address for an additional signature

6. Process repeats itself.

 I am not sure how I can make the workflow send the new task to the next individual

Any help is greatly appreciated.  Thanks in advance.

My first thought is - what is your workflow triggered by? To the best of my recollection, you can set workflows to start for a new form, or when a form changes.... I guess the concern would be, what if something in the form changes and a new task shouldn't be created? You may need some field the user can leverage to indicate intent - that is - I open the form to fix a typo, but a new to do item should not be created. Perhaps there is a checkbox I can click for "no new to do" and your workflow won't create a task if that field = true....