Recently I was asked, by a global BPM media source, to provide my thoughts in answer to the above question. There are a whole litany of reasons for process improvement failures. This fact may make some decision makers wary of forging ahead and choose to remain in the dysfunctional comfort of the "devil we know".
In my experience, there are definitely a number of causes that rise to the top of the list:
*Going out too aggressive. Attempting to tackle too much to soon. Don't attempt to boil the ocean! Small but frequent victories rein over the big shebang that never makes it to production.
*Failure to define success metrics at the beginning of the initiative and to take a baseline of your starting point. If you haven't defined success you'll not recognize it when you get there!
*Failure to reach consensus of collaboration. No department will ever get everything they want from every solution. Choose your battles and strive for the Win-Win in every system design.
*Failure to see the big picture. The more people engaged in an initiative the more viewpoints that need to be reconciled into a common consensus. Utilizing a properly trained facilitator is key to aiding the collaborative process.
Don't let your next initiative fall prey to these very preventable causes! Performing a postmortem on previous failures along with reviewing case studies will reveal that one or more of the above four causes will likely be found in nearly every case you review.