Mask(Matte) not working on Opengl mode(pc platform)

Hi everyone, recently I was confused on the mask problem when using NGUI for my project, everything goes Ok when running on the normal mode, but when I change to opengl mode(runing the exe by using commond “***.exe -force-opengl”), mask was not working like the picture I was showed, How can I fix the problem, any suggestions?

OK, I have no idea for this problem , I changed another way for my project…