distoring the colours when overlay unfilled contour on filled one
 

hello freinds,
i want to ovelay pressure line contour on the pressure contour,first i display the filled contour and turn on ovelay,and uncheck the fill parameter then i display the contour it works,....but when i do this,some part of the figure's colour distors to another for example red parts goes white!
could anyone help me please?
thanks!