In parallel with the development of a Swedish Command & Control Electronic Warfare Simulator (C2WS and LKS in Swedish) V&V (verification and validation) efforts have been made to elucidate and if possible to certify that the simulator or demonstrator as it is in its first version, is valid for its purpose. Two different methods for V&V have been employed and the procedure of the work and results, lessons learned, are documented in this report. It shows that VV&A is resource demanding, suffers from lack of standards, practical guidance and common understanding among both customers and contractors. These are the reasons for and the tasks of the several different ongoing VV&A working groups in the M&S community. The efforts of V&V in this project do not provide sufficient evidences to postulate that the demonstrator is valid for its purpose. However, a few simulation runs with the simulator show that it possesses the desired features to some extent and is able to transfer knowledge about this domain to users and developers. Further the V&V efforts helped the M&S development group to be well aware of the need of verification and validation. Also some feedback is given to the VV&A community and the REVVA method group in particular,because most of the V&V efforts follow the REVVA process.