The (sub)contractor may be in breach of contract / delaying the (subcontract) works:-
By not proceeding with the subcontract) works with due diligence, skill etc;

See: 6.1P-12.2.17; 5.0P-15.3; 4.1P-15.3; 5.1M-11.2.6; 4.0M-7.1.2; 3.1M-7.1.2 &- 6.1N-12.2.17; 5.0N-15.3; 4.1N-15.3