I have used the function and it did not return NULL. so there is no problem with this
regarding the suggestion. I should have made myself clearer. in order to load a matrix u use glLoadMatrix(...) with GL_PROJECTION or GL_MODLEVIEW as parameters. then glQueryMatrixxOES will query the matrix just loaded before its call (as in teh code snipet below).
so, if you call glLoadMatrix(GL_PROJECTION); then glQueryMatrixxOES(); you will be able to query the proj matx, and that is possible done only in the Init() function. and if you call glLoadMatrix(GL_MODELVIEW); then glQueryMatrixxOES(); you will be able to query the modelvw matx, and this can be queried everytime as the modelview is the one on top alway.