'Coupon is not valid.' Does not show up.

Hi, im using wp ecommerce and
im trying to fix my coupons in the wpsc-shopping_cart_page.php.
If you write the right coupon code it does work. But if you write an invalid coupong no message error comes up even though i have this:

<?php if(wpsc_coupons_error()): ?>
<tr class=”wpsc_coupon_row wpsc_coupon_error_row”><td colspan=”6″><?php _e(‘Coupon is not valid.’, ‘wpsc’); ?></td></tr>

How can i get the error message to show up if u write and invalid coupon code?

Thanks