You can't set the textfield in the button like this. You need to make your "buttons" into movie clips.
You can name a button in Flash MX but that is so you can target the properties of the button and use the new event model. It does not have an independant timeline like an MC and movie clips can always do more than a button.
If you use the insert target path button on the Actions panel you will see that buttons and text fields are "closed".