form suddenly stops saving created form data

I figured it out that what causes the error is when I use the pair:

add_filter( "gform_pre_submission_filter_1", "pre_submission_filter_1");
function pre_submission_filter_1( ) { }

Whenever I use this pre_submission_filter, even if the function itself has no code inside, the odd string after url starts showing. So it's something I'm missing, did I forget to do something else after the filter ?

Thanks

So, what I have to do to get some support here????

You don't need the form. The error happens when i use add_filter and pre_submission:

http://pastebin.com/ZpwE4aUY

When i let the add_filter alone or together with add_action, the error happens everytime. When i comment the add_filter, and use only the add_action, it does work bugless.

I wonder why the action works and the filter does not. They both are beeing called by form_display.

Yesterday I pinpoint the problem using a debugger with breakpoints on every $form.
I noticed that when using the add_filter, at some point in form_display.php code, the $form var turns into null (???), and a cascade of errors happens until the rest of code, ending up on the :// string after the url, the 404 error and no record savings.

I hope it helps you on fixing the issue. I'm using add_action for now, but I really would like to know why the add_filter behaves like that and the add_action doesn't. If you fix it, please let me know.

Also, what's the difference of using filter or action? They look the same to me. Are they for different purposes ?

Thanks