Mold Air Test Killed my Deal

[Duane Jones]

I have a house that I've remodeled and listed for sale.   Was under contract but buyers backed out after mold air test came back positive.  The home inspector said he didn't see any signs of mold and could not tell me where it could be.  He tested two areas bath upstairs and room in basement.  So I asked him whats the fix for this problem without seeing any mold anywhere, his answer, was to start looking behind drywall.

Has anyone ever experienced this and whats the best way to go about getting this fixed without tearing out the whole house?