I completed the example and the challenge but it doesn't seem to be working 100% or I am missing something.

For the Example, if I create a tab for it is says

java.lang.reflect.InvocationTargetException
Error is in expression '{!componentBody}' in component <apex:page> in component interview.apexc
when I go to the tab.

For the Challenge, if I create a tab and enter this information
First Name John
Last Name Smith
Company Name Misc Co
Opportunity Amount 100
Opportunity Stage Prospecting

It says
An unhandled fault has occurred in this flow
An unhandled fault has occurred while processing the flow. Please contact your system administrator for more information.

Thanks.