file_get_contents doesn't work in widget?

I want to build a widget that echoes out the contents of an html file that is in the plugin directory.

if (!empty($title))
      echo $before_title . $title . $after_title;

$resultable = file_get_contents('ii-prediction-log-widget/main-table.html', TRUE);
echo $resultable;

    echo $after_widget;

but nothing is getting echoed out to the page where the widget lies. Am I missing something?

If I manually echo out a string like this

echo ‘test’;

Then I see “test” on the page, but just not when I try to echo the contents of that html file.