Failure of a contingency plan is usually management failure to exhibit ongoing interest and concern about the BCP/DRP effort, and to provide financial and other resources as needed. Lack of management support will result in a lack awareness and training.
Source: ANDRESS, Mandy, Exam Cram CISSP, Coriolis, 2001, Chapter 9: Business Continuity Planning (BCP) and Disaster Recovery Planning (DRP) (page 163).