You have to have your account set up to get the half point rolling (applies in football, too.)
Here are their rules:
Free Half Point Rules:
* Wagers must be placed over the internet
* Offer valid on football wagers of up to $500 placed over the
internet. Sides only.
* Offer valid on basketball wagers of up to $500 placed on Friday
(PST).
* Does not apply when buying points or on / off the numbers 3 and 7 in
football.
* Valid once per game, per customer.
* All paperwork must be in order for credit card depositors to receive
a free half point.
* Once your account is set up to receive the free half point, you will
always receive a free half point in your favor unless you buy points.