Urgent advice needed!!! - should my floating engineered oak floor bounce and flex as it's walked on???

[kitsmummy]

Help please! We are in the process of having two big rooms done with engineered oak (high quality, thick engineered oak). The largest room has been done today (21ft x 14ft) The base of this room is plywood type stuff, not sure of the technical term, big sheeted stuff which sit on joists and we have a basement beneath this room. The oak has been laid on acoustic fibreboard type leveller on top of the plywood stuff.

Looks great, only problem is it bounces when you walk on it, really obviously! I'm sure it shouldn't be like this but wanted your collective wisdom on this before I discuss it with the fitter who's coming back tomorrow to do the second room. Am pretty concerned cos it looks great until you walk on it and then the movement makes it look like a total bodge job. I'm also worried that long term this movement would weaken the engineered boards.

Can anyone advise on this? thanks

Right, just to confirm, I got it wrong, it's chipboard, not plywood, does that make any difference? Also, if it is the sub-floor that's the problem, that should be something that the installers should have picked up on isn't it before they quoted and did the job? (thanks for the response, I'm hoping to be armed with info by the time I see him tomorrow, grim, I hate confrontation)

Thanks smalltown, at least now I'll be able to speak to him with confidence and conviction tomorrow!