Failed to debug draw Box2D on windows phone 8

Hi, I failed to debug draw box2d on cocos2d-x-0.13.0-wp8-0.8. Here’re my steps:

1/ Copy the GLES-Render.h & .cpp from Box2D Testbed to “HelloWorld” project (include directly the files from “tests” project didn’t work)

2/ Declare a GLESDebugDraw object in HelloWorld class

3/ world~~>SetDebugDraw
4/ Set flags
5/ Call world~~>DrawDebugData() after world->Step()

But nothing is drawn. Am I missing some steps? Any help is much appreciated. Thank you.

Giang