Robot Simulation Error. Simulation initialization failed.

In DELMIA Robot Simulation, when activating a simulation, a message appears as shown in attached pic.

"Simulation initialization failed.
One of the simulation agents cannot be initialized.
Check your simulation configuration."

Does anyone know the reason for this?

Enviroment: 3DExperience 2018x, HF4, Fix Pack CFA 1822

Thanks in advance