PHP advice – loading image broken

Hello

I’m using this free theme http://www.dessign.net/gridthemeresponsive/

When scrolling down the content the loading image seems to be broken in Safari / Chrome.

In FireFox it has no image and and just text saying loading.

This code is in the main.index page

<?php

        ob_start();
	next_posts_link('<img src="' . get_bloginfo('stylesheet_directory') . '/images/loading-button.png" />');
	$buffer = ob_get_contents();
	ob_end_clean();
	if(!empty($buffer)) echo $buffer;
        ?>

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Could anyone help me remove the loading image and just have text.

I’ve tried but I keep breaking it.

Thanks in advance

J