went to points.com, set-up a new acct for DM (my old points.com did not have DM!)
Then used the purchase miles box on the right side -was directed to the DM purchase miles site.
found this:
*Offer available for purchases made between 12:00:01 AM (MT) March 15, 2012 and 11:59:59 PM (MT) April 15, 2012. The 50% bonus for purchasing miles will be awarded at the time the purchased miles are posted to your account. You must be a registered user of Points.com or join Points.com during the offer period to receive the additional 50% bonus.
The additional 50% bonus will be awarded before June 5, 2012.
Offer available for Buy miles only. The maximum number of combined bonus miles that can be received by one member for this offer is 50,000. Offer is subject to change without notice. Offer cannot be combined with any other offer. Gift and Share transactions are not eligible for bonus. Only purchases made online are eligible for the bonus.
So the extra 50% bonus miles come later - like the first week of June!!