To efficiently solve development and software testing tasks are traditionally used teams composed of staff representing the customer and the contractor or subcontractor. The talk identifies the specific, common mistakes and typical problems in constructing such kind of teams. Presents possible ways to solve or minimize the risks created. The report is based on my own experience, as well as the contemplation of "best practice" in the field of teambuilding. Reference the classification of the teams of development/testing on the representatives. Describes the cause of mixed teams.