James, sounds like you're your :update is writing over your form
look at the partial you're rendering, and the contents, and what div
your rendering too - likely you're rendering to an ID outside the
form_tag, with a partial that doesn't contain the form_tag.
Hey James - I suggest that it's the first submit that's causing the
problem (symptom) you're seeing, when you try to submit it the second
time.
Follow the logic carefully
#1. what is the ID that your form result is rendering to? (:update
=> 'id')
#2. what partial is being rendered by your controller? What is
inside this partial?
#3. what is currently inside that ID? (on the first render)
I suggest that one of 2 things is happening:
A. the partial being rendered by the controller (in #2) is rendering
a second form - if this form is inside the current form, or has the
same ID then the Second Form Submit will fail to work
B. the partial being rendered is not rendering the Form Tag - and so
when you click to submit, the form cannot be found.
this will take some investigation on your part. But if you are careful
you should be able to find out the confusion - and learn a valuable
lesson on the way.