Hi Barbara,
Apologies for the delay in responding. To answer your questions:
If you are getting an error while doing the tutorial, please ensure that you have entered all of the inputs correctly. Note that you can always compare your model to completed versions of each training exercise by opening the Freedonia model built into LEAP. To do this, first save your own model, then open the sample dataset by going to Area->Open->Freedonia, and then Area->Revert to Version to view the relevant exercise.
If you continue to get an error, please feel free to send us a detailed message with a picture of the error and a description of the exact changes you made before the error occurred.
Thanks!
Emily