Lots of conversations around why projects fail. One of the best lists I've come across is from the UK OGC Best Practices site - with some slight edits for non-governmental domains.
- Lack of clear links between the project and the organization's key strategic priorities, including agreed measures of success.
- Lack of clear senior management and business ownership and leadership.
- Lack of effective engagement with stakeholders.
- Lack of skills and proven approach to project management and risk management.
- Too little attention to breaking development and implementation into manageable steps.
- Evaluation of proposals driven by initial price rather than long-term value for money (especially securing delivery of business benefits).
- Lack of understanding of, and contact with the suppliers of technology at senior levels in the organization.
- Lack of effective project team integration between clients, the supplier team and the supply chain