Forum Post: How to make openGL ES background transparency

I use Graphics_SDK_4_08_00_02 sdk to draw a openGL demo, but the background always black evey time openGL update the screen. I also make a Qt demo with this SDK, but the QGLWidget also get a black background.

glClearColor(0.0f, 0.0f, 0.0f, 0.0f); does not work at all.