Was looking forward to playing this properly but doesn't seem like i'm going to be able to unlock the full version of it tonight as it gives the above error screen when trying to purchase!
A quick google search reveals this is a widespread problem with users all over the world, i don't think even SNKP have realised yet judging by the fact they've just updated their Facebook page with the status:
Hi everyone! “TROUBLE☆WITCHES NEO!” is available on Xbox LIVE Arcade for the small price of 800 Microsoft Points! Get on your broomstick and experiment alone, or with witches worldwide, in the cutest shooter ever on your Xbox 360!! Alakazam!!
It's a real shame, as judging by the trial version, it seems like a decent game and visually quite stunning. I think i may just finally just get around to playing the PC version instead until they manage to sort this out...Hopefully it won't be too long.