Current Advanced Planning Systems in the market: which are their weak spots?

 Subject Matter Expert: Planning, Scheduling and Execution Solutions for Manufacturing, Supply Chains and Services

Which are the industries where most implementations of APS have failed? And Why? Lack of functionalities? Lack of a suitable architecture? Lack of domain and product knowledge? …

Are there still Planning & Scheduling processes that are not yet well covered and that are business critical? Which ones?

Any feedback is highly appreciated,
Thanks Fabio