You probably forgot to import RoboticsCust customization in your eMServer schema. It is under eMPower\InitData\RoboticsCust.
I tried to follow your advice and import RoboticsCust customization, but got another error message.
The message is self explanatory, you need to go to Admin Console and close all eMS session before you can import a customization.
And disable login as well? You should have no more sessions alive in Admin Console.
I do not have more clues.
To import the customization, you cannot have any Project loaded. When starting PS, at the Open Project dialog, hit Cancel; or if in PS and a Project is open, Close the project. Then try to import customization again. The user must be administrator, or a user in administrator group with proper permissions for the schema.