Will, yours returned expired, however this one below from last year still worked.
Gave me 3 to use until January 31, 2015.
I don't do auto investing with share builder, but I do use it to buy and hold limited individual stocks like BRK-B.
Found another that works too:
3AIP
update: just got this in an email from SB.
Don't forget—there's an expiration date on your credit(s): 01/31/2015. (Actually, the last Tuesday of the expiration month is the real cutoff.) So take advantage while you can.
Credit(s) will be applied when you update your Automatic Investment Plan and your scheduled orders are placed. Start now.
That promo is only good for AIP credits, not trade credits.