WordPress and $_GET Params

This is an odd problem that I have never run into before with WordPress.

I have a site, permalinks enabled.

The url can be http://mysite.com/page-name/?anyParamName=testing

then when I use print_r($_GET); or echo $_GET["anyParamName"] I get an empty array or nothing respectively.

A pure PHP file works fine so its not a server issue. Does WordPress do anything with rewiring the get params? Really puzzled by this.

For custom parameters you should register them with WordPress:

add_action('init','wpse46108_register_param');
function wpse46108_register_param() { 
    global $wp; 
    $wp->add_query_var('anyParamName'); 
}

Then the value of ‘anyParamName’ can be found with get_query_var

$anyParamNameValue = get_query_var('anyParamName').