Magento

Hi Folks -

We have an issue with tax not being added to orders.  We tax in only one state: TN.  The tax rate is set properly and configured to the shipping address.  The products in question are set as taxable goods.  Test orders for the state in several configurations (selections of several different products as well as an order with products from an actual order where we had the issue, same ship/bill address, separate ship/bill address, etc) all come through with no tax attached.  Please assist!