Who Is Responsible For Foundation Cracks In My Condo Unit?

I attempted to install hardwood flooring in my unit. When the carpet was pulled the workman found that the entire concrete sub floor was cracked. It looked like sand! The association has not responded to my request for payment for the repair of the concrete. Please confirm that is is the responsibility of the association. It is not covered under my condo policy. I was advised by my insurance broker that it was the associations responsibility.