WordPress Chat Configuration

I just purchased this plugin, and it doesn't work. It installs, and you can see it embedded on the page.
- type chat text
- hit enter
- nothing appears

So I tried it on one of my other sites to see if I had more luck.
- type chat text
- hit enter
- nothing appears

Then - I click on the screen where the chat is supposed to appear - and the chat appeared.

Wouldn't be good if it worked this way, but thought I'd try the same thing on the first site. No luck.

So then I tried it with a brand new site with the TwentyTen theme - and it worked. I switched to another theme from a specific company - and it no longer worked. (no other plugins are activated). I switched to another theme from yet a different company, and it didn't work.

Not a happy camper.