(digging effect) RenderTexture draw issue on some devices

Hello,
In one of our projects, we use CCRenderTexture; the goal is to make the rendertexture transparent at the touch position in order to see the sprite below (digging effect). After testing on different devices (asus nexus 7, samsung galaxy tab2, galaxy S, galaxy s2, galaxy note, galaxy note 2, galaxy nexus, nexus S, htc one x, htc one s), we have found an issue with the HTC Desire S.
Instead of having the digging effect, the renderTexture seems to be blended.
Here is a video showing what it should do (on the left - an HTC Desire with a custom rom using android 4.2) and what it does on the HTC desire s (on the right - official rom).

Does anybody know how to fix it, or the difference between this device and the other that we have tested(opengl version) ?

You can help me how to draw with CCRenderTexture, please. Thank you.