CANCELLED: 23.3 Exercise 5_ Records Part 1, Accessing Your Data.pdf page 12: Edit Record List Columns - I am getting: Invalid index operator ''vehicle'' (expecting comma).

Following all the steps in 23.3 Exercise 5_ Records Part 1, Accessing Your Data.pdf
Page 12,
In the Expression Editor, delete all text, and enter the following expression:
if(a!isNullOrEmpty(fv!row[recordType!AX
Vehicle.fields.image]), a!EXAMPLE_DOCUMENT_IMAGE(),
fv!row[recordType!AX Vehicle.fields.image])

I enter that, make sure it's formatted well, but the "OK" button does not get enabled.  The red triangle says 
Invalid index operator ''vehicle'' (expecting comma).