Get great savings on tickets to some of the best in entertainment
Offer Valid 08/01/2006 - 09/30/2008

At the American Express Ticket Savings Center, Cardmembers receive special savings of at least 15% to a wide array of entertainment events. If your passion is music, sports, the arts or family attractions, just go to the Ticket Savings Center to enjoy the savings and the show. New offers are added frequently, so visit the Ticket Savings Center at www.Ticketmaster.com/amexnetwork often.

To access the offers, simply use your American Express® Card and enter promotion code AMXNET during checkout.

link
---------------------------
From what I understand, the listing of tickets on the AMEX page is already discounted and in order to get the discount, you must enter the code. The code does not give you an extra % off when you enter it into your cart or on checkout.

For example:
Mamma Mia tickets were $110 or $82.50 (2 options)
AMEX site shows 40% off: $66 or $49.50 (2 options)
Final cost: $66 or $49.50 + Ticketmaster fees (about $12)

I am trying to Buy US open ticket...the password or promotion code AMXNET is not working for me.

Unless I'm missing something, the thread title is misleading. It isn't 15% off anything, its just special offers on select events.

I tried still not working, may be I am doing something wrong.