Controller function not finding $_GET variable for jQuery Autocomplete

[eluser]Fielder[/eluser]
I've been hacking away at this all day and searching manuals and forums... still stuck (although I've found a work-around by NOT using a controller/function url).
*Consider all javascripts properly loaded and view setup correctly*

My jQuery is

Code:

$("#storeAutoSuggest").autocomplete("/rtui/codeigniter/index.php/storeform/autocompletestore");

The jQuery plugin documents

For remote data: When the user starts typing, a request is send to the specified backend ("my_autocomplete_backend.php"), with a GET parameter named q that contains the current value of the input box and a parameter "limit" with the value specified for the max option.

A value of "foo" would result in this request url: my_autocomplete_backend.php?q=foo&limit=10

So in my storeform/autocompletestore controller, I have

Code:

function AutoCompleteStore()
    {

//TODO:: does not function with jquery autocomplete. When loading storeform/autocompletestore it does not see the "q" variable in the url
        $q = strtolower($_GET['q']);
        if (!$q) return;
        $items = array(
        "Green Heron"=>"Butorides virescens",
        "Solitary Sandpiper"=>"Tringa solitaria",
        "Heuglin's Gull"=>"Larus heuglini"
        );
        
        foreach ($items as $key=>$value) {
            if (strpos(strtolower($key), $q) !== false) {
                echo "$key|$value\n";
            }
        }

    }

I get "ERROR undefined index: q".

I know the jQuery and my form view works, because instead of loading the controller/function as I want above, if I simply load an external .php
<like this>

Code:

$("#storeAutoSuggest").autocomplete("/rtui/codeigniter/system/application/views/include/search.php");

with the exact same code in my function - it DOES work.

But I want to be able to manage the array, data, and database query calls from inside my controller.
Any thoughts?