Can't change change thickness of stroke path by brush

I draw a simple path with the Pen tool.  Go to brushes and set the brush to desired size and shape. Go back to Pen tool and click on the path and choose "Stroke Pen", then choose "Brush" (leaving simulated pressure off). Every time a path stroke is the same exact width regardless of my brush size. I can change the brush to 10 or 100 pixels; stroke always looks like it's 5 pixels thick... I'm stuck, please help me...

Attached is a screenshot of the actual brush size (in the middle) and path stroked with this brush...