How can I make my strokes appear within a pen tool drawn shape?

I have drawn an outline of a picture using the pen tool. And then I have use the line shape to draw some lines within the outline. I grouped the lines and the outline together to make one giant shape.

When I fill the shape with a fill colour or pattern, for some reason the line shapes within the pen tool drawn outline does not appear! it's as if the line shapes are underneath the fill, but I've tried "bring to front"and it still doens't work

what am I doing wrong?