Balanced Reporting on Six Sigma Performance

Following a recent post regarding engaging reluctant senior management (thanks for all the advice), I am seeking to understand instances where six sigma has failed to live up to expectations. I want to be able to present a balanced argument for six sigma and therefore need to at least demonstrate an awareness that six sigma is not a simple and undeniable fix for every problem. I have already picked up frustration from this forum where it is not running as smoothly as possible - champion system broken, no engagement of middle management / senior management, no exec support, no green belts. I am looking for examples of failure where the scheme has been abandoned or seriously jeopardised, and the reasons behind this failure.

I am also seeking examples of manufacturing business success where the principles of six sigma have not been employed.

Many thanks for your continued support

Tim