Glad you figured out what I was trying to convey!
When you created the notification context, did you specify Tango under "Owner Application?"
For example, I created one with gmail set as owner:
I tried this with a Notify LED task, and it did work for me, but I think it failed to work the first time I tried it. Also, I can tell you that I tried the Notification Click functionality a few weeks ago. It sure seemed like I was doing everything correctly, but I never did get to work. So maybe Tasker's notification functionality isn't 100% robust on all devices ... I don't know. (I'm using an HTC EVO 4G, BTW.)
Are you absolutely certain that the event never fires? Is it possible that it's firing, but it is the task that's failing? You could verify that with a debug line of some sort as the first element of your task, maybe Misc->Say to output an audible verification, or Alert->Flash, for a visual verification.
If you have configured a context owner app, as well as some kind of task debug output, and it still isn't working, maybe you could try a different owner app, (e.g. gmail, or messaging) just to see if the problem is unique to Tango for some reason.
Good luck, I'm curious to hear how it goes.