Specific widget on specific page

Hey all,
I’m trying to set up a php if else statement that will tell wordpress to show specific widgets on specific pages. Here’s what I have so far, but it’s not doing the trick:

<?php if (!is_page('contact') && function_exists('dynamic_sidebar')) {
dynamic_sidebar('Contact Sidebar');
else if (!is_page() && function_exists('dynamic_sidebar')) {
dynamic_sidebar('Sidebar');
} ?>

If someone could help shed some light on this I would appreciate it.
Thanks!