There might be different reasons for this issue. The following is a list of some of the more common causes and the solutions.
1. If rUsers are not created, make sure that the password meets the requirements for the Windows machine hosting the Injector. For example, Windows Server 2008 requires passwords to include characters from three of the following four categories: Upper Case, Lower Case, Base-10 Digit (0 through 9), and Non-alphabetic (i.e. !, $, #, %).
2. If rUsers have been created and the rUserManager has opened on the Injector, yet rUsers cannot be started in the rUserManager, there might be an issue with Remote Desktop Connection. This issue can be solved by adding the “Remote Desktop Services” role to the Server. Please refer to the appropriate “Windows Server Optimization for Injector” document to learn how to properly configure the Server for optimal use as an Injector. You can download it here.