We delivered information system for a production line. Part of delivery was also an application for users in production. Analysis and high level design was approved by the customer representatives. At the beginning of implementation phase we have found out, that the application for users will not well match the user's needs (a foreman of production line was very critical). We relied on the information we got from customer's bosses, but it was not sufficient.
Although the customer accepted the first design, we rebuild the application according the information of the users from production line. Due to this the project delivery was delayed, but we agreed it with the customer before. At the end they were very satisfied with delivered system and application.
Provide carefully the stakeholder identification and management. We fall back with the official customer's project partners and almost lost possibility to have right informations and strong supporter.