There are 2 famous Harvard case studies pertaining to failed ERP implementations..... Nestle and Nike. Both were attempts at implementing SAP, but it could have been any software as the reasons for the failure weren't the fault of the software manufacturer. The common thread of both failures was a deficiency in the needs analysis.
In both cases the department heads, controllers, IT people et al had many meetings and planning sessions to hash out the details of the new system. Processes were documented, features were designed, and programmers and consultants implemented the code changes.
The go live was a disaster. Users couldn't or wouldn't use the software. Incorrect SKUs were sent to customers. Millions of dollars were lost in costs of software, consulting, inventory, and customer goodwill.
Both Nestle and Nike started from scratch. What did they do wrong the first time? They didn't involve the employees actually using the system. Most end users weren't involved in the ""high-level"" meetings. management decided that ""this is what we need"" and tried to shove it down the throat of the order takers, AP and AR clerks, and shipping and receiving personnel. The lessons learned were: You need to involve the users of the software in a new implementation. Every keystroke, menu, job function, and feature needs to be examined. If a process needs to change, the person doing the work needs to be involved. Make the user feel they are a part of the implementation team so they have some ""buy in"" on the project.. When a user feels they were part of the team helping to improve the company they are far less likely to reject the software and the ""the old system used to do this"" is minimized.