I have also seen project that failed or cancelled or shrunk. Why is it happening when so many intelligent people are working and we know all the ingredients of project success? Here are some commonly known factors needed for project success -

Timely user community involvement and input

Well defined project goals and requirements

Realistic expectations and deadlines

Proper planning and right methodology

Open and clear communications/directions

Motivated team with sense of ownership

Watch out for signs of failure - conflict/politics/cover-up

Positive attitude - every day and towards everyone

Correct estimates (beware of inflated estimates)

As any project manager (PM) knows success is dependent on controlling three constraints - Time, Scope, and Cost. Any mismanage of these three constraints results in project failure. Above mentioned 6 points can have direct impact on the three constraints namely time, scope and cost.

What else is important and needed to make sure project is success? Your thoughts are welcome.