Submit POST form when rvest doesn't recognize submit button : <p>I would like to submit the following form (the form appears after you click on link "Kliknite na ..."): 
<a href="http://www1.biznet.hr/HgkWeb/do/extlogon" rel="noreferrer">http://www1.biznet.hr/HgkWeb/do/extlogon</a></p>

<p>I have to enter one parameter, named "OIB" and submit the form by clicking "Trazi".</p>

<p>Here is my code:</p>

<pre><code>library(httr)
library(rvest)

sess &lt;- html_session("http://www1.biznet.hr/HgkWeb/do/extlogon")
search_page &lt;- sess %&gt;%
  follow_link(1)
form &lt;- html_form(search_page)[[6]]
fill_form &lt;- set_values(form, 'clanica.cla_oib' = '94989605030')
firma_i &lt;- submit_form(search_page, fill_form, submit = 'submit')
</code></pre>

<p>Last line produces an error:</p>

<blockquote>
  <p>Error: Unknown submission name 'submit'. Possible values:
  clanica.asTextDatumGasenjaTo, clanica.asTextUdr_id</p>
</blockquote>

<p>I don't understand why rvest recognize this two parameters as submit buttons when they don't contain submit name or type. And why rvest doesn't recognize submit button "Trazi" as submit parameter? In, short, how to change filled form to execute the form?</p>
