NOTE: when creating a tax rule to trigger off the ecart session values, the tax will not be applied untill the user submits the checkout page and gets to the confirm page.
add the following to the body of your confirm page to see what the session variables value is:
<?php echo("Shipping State: ".$_SESSION["eCartCheckoutForm_shipping_state_province"]."<br />"); ?>
this will tel us what is being stored in the eCartCheckoutForm_shipping_state_province session.