Video Filter Question

Try adding it from the Menu Effects>Video Filters>(filter of your choice)

It is quite possible that the filter you are applying (you don't mention which one) is set to values that do nothing at first because they need to be activated.

Click the clip to which you have applied the filter, twice.
In the Viewer, click the Filters tab. Make your adjustments using the controls there and you will see the changes reflected in the Canvas.

EDIT: you posted whilst I was replying to your original question.
You can't apply an effect to a blank timeline.

Message was edited by: Nick Holmes

You need to add it to a clip, even a color solid, but not to empty space

you can add "Lens Flare" to the timeline without placing it on a clip, i just forgot how to do it.

No you really can't technically.

But you CAN add it to a slug. Sounds like that will work for you.

Then in that case, it's a Generator, not an effect.
Two different things.