My brush tool won't work on my second layer! It keeps giving my the circle with the line through it.

[Jennifer228441401aza]

Help! I'm new to Illustrator and I'm trying to draw with the brush tool. But every time I click on the brush tool and try to use it, I get a circle with a line through it at the curser. I have two layers and the 2nd layer is the one I'm trying to use the brush tool on. Does anyone know hwo to fix this? 

[Monika Gause]

Are there brushes in the brushes panel?

Other than "Basic", which is not a brush.