One possible solution is that your browser is not setup correctly.
Under Internet Explorer, Tools (View for older versions of Internet Explorer),
Internet Options, left mouse click the Security Tab.
Drag the security level bar to Medium as shown in the following picture:
(A Security setting of High disables cookies)
Under Netscape, we have not encountered any problems to date.
Another possible cause is that you are trying to order a product that is out of stock.
Click on the product name to check for availability.
If you have any additional questions or if the above procedure does not fix the problem, do not hesitate to email firstname.lastname@example.org.