Issue while adding custom field in billing address

Question

I followed this tutorial for inserting new field in billing address section in Magento checkout.

I added new module, form field in billing.phtml page as described in this tutorial. I make sure that the module is enabled in advanced section in admin panel. And the attribute is saved in eav_attribute, sales_flat_order_address, sales_flat_quote_address tables.

The issue is when I make place order the checkout page become broken and nothing can done.

How can I solve this? Please help..