202 In our opinion, there is a fatal fallacy that underlies this approach. Like the method adopted by the learned Judge, it rests on the proposition that the only source of profit to Thiess was the contractual 5 per cent (and, presumably, cost underruns and productivity gains). We have held that there were, however, several other sources of profit. It may be that, utilising the Project Forecasts in the way we have postulated, it would be possible to determine the costs incurred and revenue received from each category of work under the contract. But, in order properly to calculate damages in accordance with Placer's method, the profits earned from all sources would have to be determined. The burden was on Placer to prove such profits. It made no attempt to discharge that burden. We have pointed to the fact that the absence of evidence in regard to profitability factors meant that the learned Judge was unable to calculate productivity gains on load and haul. There was no evidence of cost overruns and underruns in areas other than the internal plant department. As we have mentioned, the productivity gains in the plant department that were assessed were for a limited period of time only. There were other sources of potential profit in respect of which there was no issue at the trial. Placer did not attempt to prove the amounts of profit, if any, Thiess made from all relevant sources. That being so, the way Placer, at trial, attempted to prove its damages was bound to fail. There was a crucial lacuna in its damages formula. In the result, Placer did not prove its damages.