Other people have posted this but there does not seem to have been a conclusive answer.  I'm new to Trailhead and have become quickly addicted to completing the challenges, which are a great way to learn more about Salesforce functionality.  Unfortunately I've just had my first challenging experience.  Like others that have posted about this, I am pretty sure what I have done is correct, and I've double and triple-checked and can't see what's wrong.  I'm getting this error:


Here are the fields I've created in the Object:


Can anyone see anything that I've done wrong?

Many thanks for your help!


Ryan