Hello,
difficult to say - based on the provided information.
Are you able to build the examples (e.g. Hello World) according to the Getting Started documentation? Are these running on the target?
If you already have executed the MasterDemo successfully, but now you got some exception when you try it again, please make sure that the hardware and the RasPi configuration is still the same. Please make sure that the touch device is working properly. This causes sometimes problems, when there is no touch connected or configured incorrect.
Best regards,
Manfred.