If a market is set up with price floor = 0, then the demand/supply intersection is never calculated. The algorithm reports a null intersection even if some buyers is willing to pay more than the price a seller will take.
This bug has been located. It is in inc.d/f_economy_Q_demanded.inc:
remove the line that says
if ($price <= 0){ return( arrray(0,0)); }
This line is near the top.
This line is appropriate for supply (since at P=0, there would usually be no supply) but not for demand. At P=0, there is usually lots of demand.
