Tax not working

I have set the following under System > Configuration > Option > Taxes…
Use Store Tax Address: None
Use Customer Tax Address: Shipping Address

Then I create a Geo Zone for Texas, United States. I created a Tax Rate of 8.25% for Texas. Finally, I create a Tax Class named "Taxable Items" and assigned the Texas tax rate based on Shipping address.

In each product, I set Tax to "Taxable Items". At checkout I test using Texas address for billing & shipping, but I am not seeing any tax in the cart.

Found the problem. I had not set the default customer group in System > Configuration > Account

That's correct!
Sincerely, Giang