Solid Hardwood, Engineered and Laminate Flooring - Urethane on hardwood floor

We just recently insalled a hardwood floor, actually 12,000 + sq ft to be exact but the urethane that we had put on seems to be coming off, like dust almost. Is this commomn? or did we end up with some cheap stuff, or is there another explaination for it. Any help wood be greatly appreciated

"just recently insalled a hardwood floor" - meaning what, site or pre finished?

it wasn't pre finished it was unfinished maple. Then we urethaned over it with roughly 3 coats. of polyurethane.

Similar to my project, I just refinished it. Resanded - one coat stain - 2 coats Minwax fast-drying poly-u. No probs.
What were the manufacturer's instructions. Per my Minwax application... if you go beyond 5 hours between coats, you have to do light sanding in-between - clean - and recoat. Or, you can directly apply the next coat if you do that after 4-5 hours (the coat is strong enough to be lightly stepped on but not fully cured).
Basically, once the poly-u is fully cured then "nothing" will adhere to it (light sanding creates that bonding surface). Question is: did you wait too long (per instructions) in-between.

yes we had sanded lightly inbetween layers, thats what someone else had asked us also. I mean it is a big area, and being that everyone skates on it I thought it might just be wearing. If I wasn't the one cleaning it all the time I probably wouldn't even notice.