Some games missing from DSi Shop. What Am I doing wrong?!?

Hi, I got a DSi and logged onto the shop to buy Bejeweled Twist and Bookworm from PopCom. In spite of it being advertised on the nintendo site as being in the shop, I can't find them anywhere. :mad:
In fact, a lot of games advertised do not appear in the shop. Is this a region thing or have I messed up somewhere along the setup process. I set region to Ireland and parental controls are off; two things that may have cased the problem. Any help appreciated