For Chicago Public School students, please use the first part of your CPS email as your Aspen Id.  For example if your CPS email is:

Then your Aspen Id would be student34.   
You can also try to log into Aspen using a browser like Safari or Chrome and test your credentials.  If that doesn't work, then you'll need to contact your school administrator to reset your credentials.  

Once your credentials are working, simply update them in Grade Corner and you should be all set.