Help me! qa-theme-base.php

Question

I have created a category "QWERTY" and I want that questions from this category will be showing only on the page of this category (http://localhost/?qa=questions&qa_1=QWERTY) and not on "recent", "hot" etc.. I changed the code from qa-theme-base.php from

function q_list_item($question)
{
$this->output('&ltdiv class="qa-q-list-item'.rtrim(' '.@$question['classes']).'"&gt');

$this->q_item_main($question);
$this->q_item_stats($question);
$this->q_item_clear();

$this->output('&lt/div&gt <!-- END qa-q-list-item -->', '');
}

to

function q_list_item($question)
{
if($question['categoryname'] != "QWERTY") {
$this->output('&ltdiv class="qa-q-list-item'.rtrim(' '.@$question['classes']).'"&gt');

$this->q_item_main($question);
$this->q_item_stats($question);
$this->q_item_clear();

$this->output('&lt/div&gt <!-- END qa-q-list-item -->', '');
}
}

But it not works. Why? Help me, please.
Thank you for advance.