land titles for apartments

I bought an apartment about 4 years ago with a private courtyard. The developer put all of the courtyards on common land and did not register the new plans with the land titles office. We are on 99 year leases instead. This has not been a problem until my neighbour tried to sell his place and found he has old carparks in his courtyard. Now he wants us all to contribute $1000 each to have the problem solved. He is the only one affected as others have been bought and sold without problem. Not sure what to do.