Just downloaded Zen Pinball 2 and the Plant vs. Zombies table. When you click the trophies icon on the game it tells me to buy new tables. I thought I just did... Is there just no trophy support for that table?
There is indeed a problem with the trophies for Zen Pinball 2 on the PS Vita. According to this Tweet Zen Studio's is working on it.
Apparently it is location related. It affects users in the EU and it's still not fixed.
Trophies appeared on the PS Vita for me after I bought the Avengers Chronicles pack even though I installed the classic tables pack. On the PS3 the game just unlocked (and had trophies) after installing the classic tables pack.
Looks like there are a couple of trophies associated with the Plants vs. Zombies table, see the bottom of this page: