Brush color changes if I go over the same stroke

[Anonymous]

I'm very new to this, and I don't know a lot about this software, but I'll try to be clear.

I draw on paper and then upload it to my computer to color. I use brush strokes with not 100% opacity so that my pencil lines from the paper can still be seen, like this.

However, when I go over the same brush strokes to complete coloring in, the lines get darker like this.

Does anyone know how to make the brush strokes one solid color when their opacity is less than 100%? I know I could achieve this by just drawing in the program, but I don't have a tablet and would prefer to keep using pencil and paper. 

Thanks!

[david.lau]

It depends on the brush you are using.  If you choose a pencil or paint brush, its should be opaque.  If you have a Wacom tablet, it will be pressure sensitive. The harder you draw, the darker the color.

http://help.autodesk.com/view/SKETPRO/ENU/?guid=SKETPRO_Help_sb_brushes_what_are_brush_types_html