Same thing happened to me at a Sprint store. My Pre was activated, but... no EV indicator.
When I tried to sign into my Palm Profile, it gave a "Try Again" message that said something like, "data not available, go to an area within the Sprint data network." The guy helping me in the Sprint store did a couple of 'soft resets', but still...no EV indicator.
He then called someone in Sprint tech support and did a "master reset", re-activated the phone, but still...no EV indicator.
Then, the in-store 'Pre-advocate' lady got involved. She said her Pre had the same, 'no EV indicator' problem when she activated her phone. Go figure. She said her EV indicator "just showed up after waiting 10 or 15 minutes." So we waited, but after 15 minutes still...no EV indicator.
I'd been there a while, so the store manager came over and said I could switch it out for another Pre. Ironically enough, the Pre-advocate said, "let me try one more thing" and she called Sprint tech support again. She was on the phone for at least 15 minutes (I have no idea what she was doing). All of a sudden...POOF! Magically, the EV indicator was back!
I asked the Pre-advocate, "what was the problem?" She said, (referring to the Sprint tech support person on the phone, "it was something on their end." So I guess, Sprint tech support pushed the magic button to make it work. I just wish I knew what that they did exactly so I could let you know. I'd been there for so long, I was just happy to get my Pre working and out the door.
Since then, I've had zero problems with the Pre. So, my uneducated guess is that it's a problem on the Sprint side of things, not with your Pre or anything you did during activation. If I were you, I'd try calling Sprint and telling them your EV indicator isn't showing up. Maybe that will get them to push the magic button that will make it work.