I installed the windows 10 adk and started the deployment tools command line. dism runs ok and reports its version 10.0.10240.16384. If I explicitly run from "c:\Program Files (x86)\Windows Kits\10\Assessment and Deployment Kit\Deployment Tools\amd64\DISM\dism.exe" it also works. I am running windows 8.1 x64 enterprise edition.