Wood Floor Installation Problems

Just finishing a lot of work with what has been over all a good experience with our contractor. The work was done 50% below grade. We used a click lock engineered bamboo floor, as engineered is suggested for below grade installation. Before installing the floor, he put down a subfloor on top of the concrete. The sub-floor is particle board with a ridged hard rubber moisture barie attached onthe underside to sit on the concrete. The floor was just installed 5 days ago, and we still have lots of spongey areas where the flor gives a little bit. Is this a result of the subfloor not being level? Should our contractor have warend us or automaticly taken steps to level the subfloor before installing floor? Info & suggestions appreciate.