I'm using OpenGL ES in my Windows Mobile 6 application, and I wanted to enable vertical sync by using eglSwapInterval. The parameters I supply are: #1: m_display (a valid GLDisplay variable, created in prior steps) #2: 1 (the update interval) But the eglSwapInterval function returns GL_FALSE. I even tried changing the second parameter to 0, just to try turning vsync off, but that resulted in the same return value. I have not made anything special to the config attributes involving EGL_MAX_SWAP_INTERVAL or EGL_MIN_SWAP_INTERVAL. Do I need to declare these in the attributes, or do they simply use the default value (GL_DONT_CARE)?