Gallery short code

for a normal gallery i use this code from the php:

<?php echo do_shortcode(‘[gallery]‘); ?> or i specify the id with using <?php echo do_shortcode(‘[gallery id=41]‘); ?>

i am using a plugin and if insert this [polaroid=41] from the wp panel it shows the gallery in the page, while if try to call it from the php it echo [polaroid=41] on the page but no gallery.

Any idea why?