Emailed ticketmaster about the Housto show not showing up.
This is what they sent back to me:
Thanks for your email and we hope all is well!
We can't find a date for Katy Perry in Houston on our system, which means one of two things:
•This even isn't showing up yet--
keep checking Ticketmaster.com for updates (search by artist at the top and click the artist name on the next page for a list of dates)
•We aren't selling tickets for this event--Check the artist's website for details
Don't see it on livenation either. It is listed on Toyota Center but no details on where or how to buy. Tweeted their twitter for the center's tickets and waiting for a reply.