Using sidebar widgets in multiple sidebars

I’m having trouble getting sidebar widgets to work in multiple sidebars. I have widgets working correctly in one sidebar. I changed the code in functions.php to the following

if ( function_exists('register_sidebars') )
	register_sidebars(2, array('name'=>'Sidebar %d'));

And I now see Sidebar 1 and Sidebar 2 in my admin screen. The first sidebar (which was already working) still shows up. But when I add the following code in the sidebar.php file, to call the second sidebar widget, both sidebars and the main content disappear:

<?php if ( function_exists('dynamic_sidebar') && dynamic_sidebar(1) ) : else : ?>

Any ideas? I haven’t been able to find any clear instructions for using widgets in multiple sidebars, I looked at the API documentation on the Automattic site, but I’m pretty new to PHP, so I may be missing something.
Thanks in advance for any help!