First check which config you are using - how many bits for each color channel (are you using RGBA 8888)?
Next check if the eglCreateWindowSurface() succeded [eglGetError() == EGL_SUCCESS].
If all is ok at this point, keep in mind that the default VG blend state is SRC_OVER_DST if memory serves. As such you will be blending the translucent white with the default black background producing a gray color. Try clearing with a different color (like red) to make sure this is not what is happening.
Also I don’t see your call to vgClear(). You need to call vgClear after setting your clear color - just setting the clear color and calling swapbuffers will have no effect.