Need help in using the clone tool.

Here are the steps I am using:

I zoom in on the area using the zoom tool.

Then I go to the clone tool and pick the first one.

I go to the color that I want to clone.

I then bring my cursor to the area that I want to change to the new color

When I do this nothing happens. It won't erease or change the color.

Can anyone tell me what I am doing wrong?

Running CS3

Windows Vista

Alt+click to pick up the source area.

Click and paint in the target area.

In the Options bar at the top make sure "Mode" is Normal and "Opacity" is not too low.