Hello again Max,
Make sure that
Tobii.EyeX.Client.Net20.dll has been copied to the root of the build (where the built executable reside).
EDIT Jenny [Tobii] 07 Feb 2017: Above info is not correct. Only the Client dll should end up in the root, the managed Net20 dll ends up in the Managed folder in a standalone build. See post #6306 below for more info.