Oops! We could not locate your form - tied to call in functions.php

I have read through the other "Oops!" posts and have tried the Meta Recovery Tool on my form as well as changing to a standard theme but I still get the following pattern:

I have 2 forms. One of them (form with id=2) works fine even with a lot of custom filters in the functions.php file. The other one (form with id=1) works fine as long as I don't have any code for that form in the functions.php file. As soon as I add any code trying to work with that particular form, I cannot preview or use the form - I get the "Oops!" message.

As a test, I tried adding this to my functions.php form and it breaks:

[php]
add_filter("gform_pre_render_1", "setup_item_order_form", 10, 2);
function setup_item_order_form($form) {

}

If I add:

[php]
add_filter("gform_pre_render_1", "setup_item_order_form", 10, 2);
function setup_item_order_form($form) {
     echo "hello";
}

Then it shows this when I load the page containing the form so it's getting to the pre-render:
hello
Oops! We could not locate your form.

If I remove those lines, the form runs fine with or without the custom code that is there for Form #2.

Any ideas?

Setup is:
Gravity Forms: 1.6.11
WordPress: 3.5
PHP Version: 5.3.2

I found a way around this. I'm using the generic "gform_pre_render" filter instead of doing the forms separately, e.g. "gform_pre_render_1" and "gform_pre_render_2"

Then, within my gform_pre_render function I'm using:
switch ($form["id"]) { } to provide chunks of code that apply to the specific form being used at the time.

I guess it doesn't want you to have more than one gform_pre_render_* filter at a time even though they are for different forms.