I was assuming that the field name was a variation on Phone, but obviously the problem was that the field was called Cell, not Phone. If the field name is changed, the code has to be changed to reflect the actual field name.
The original error message told you exactly what the problem was: that there was no field named Phone.
I think I see what happened. At the bottom of this page:
it says "To examine or change the options, simply click on the Properties tool to open the Field Properties Panel. For example, I can use this panel to change the Phone field to Cell."
However, it was really not meant for you to change the field name at that point, just to show you that you could do that if you wanted to. Sort of a "Simon says" situtation, and I agree, a bit confusing. I have just added a note there to clarify that if you try changing the field name, you should be sure to change it back before continuing with the tutorial. The link on the web page above already has the correction, and the embedded help system inside Panorama will include it when the next release comes out.
If you run into any other confusing points in the tutorial, I'd be happy to see if we can clarify them as well. We proof read everything carefully, but as in this case it is still possible for something to slip thru.