Hello,
If you'll take a look at components/com_rsform/controller/adapter.php (latest version of RSForm! Pro, of course), on lines 59 and 60, you'll see that we've already added this code:
$cache =& JFactory::getCache('com_rsform');
$cache->clean();
However, this code has only effect when you access RSForm! Pro through index.php?option=com_rsform.
The System Cache Plugin works like this (we'll be using the example of RSForm! Pro loaded in a content article):
- the article is loaded;
- the RSForm! Pro Content Plugin runs and replaces the placeholder {rsform 1} with the specified form;
- the System Plugin records what the page looks like and saves it in the cache. This means that from now on, the page will never load the RSForm! Pro Content Plugin, and RSForm! Pro will never run as it should (the form will get displayed because it's appearance is stored in the cache, but the functionality is not).
There is no way to stop this from happening, unless you disable the System Cache Plugin. Unless the System Cache Plugin is modified to accept new parameters, there's no solution.
Take a look at the code of the System Cache Plugin, located in plugins/system/cache.php, and you'll find this comment from the Joomla! Developers:
// the following code searches for a token in the cached page and replaces it with the
// proper token.
So, they are aware of the problem and they did a little hack so that the token of the forms (a hidden field containing a secret token) gets replaced with the proper value, so that the standard forms in Joomla! (search, login, register etc) work.
We're trying our best to come up with a fix, but no luck so far. I hope this solves the "mistery" of the System Cache Plugin.