Problem with a simple TRIAC simulation

[Koala]

Good night everyone.

I am trying to do a dimmer but I could not simulate it.

The circuit:

http://img.photobucket.com/albums/v222/ahhh/triac_1.jpg

And the result:

http://img.photobucket.com/albums/v222/ahhh/triac_2.jpg

Problem: The TRIAC is always conductin...

Well, when the signal goes to 0V, it is suposed the it not conduct.....

Proteus 7.8.

Thanks....