Why would the Project Manager reject the Contractor’s design?

Why would the Project Manager reject the Contractor’s design?

There are only two reasons why the Project Manager can reject the design: either it does not comply with the Works Information or it does not comply with the applicable law.
If the reason why the Project Manager has not accepted the design is not either those reason or if the Project Manager did not reply within the period of reply, then the Contractor may notify the Project Manager of a compensation event.
If the reason for the non-acceptance was in the contract and that the Contractor does not agree, he can notify a dispute in accordance with the contract.