Question Re build an application step 9

I am re building the Dev training app and this is only thing I cannot get to work from the training guidance and I am not sure why.  I have rebuilt up to step 13 and every thing else and other tips have worked. 

On the add Vehicle form.

a tip is "TIP: Use the Visibility Setting to Conditionally Show Interface Components ● In some cases, you might want to display a component based on a condition. ● To do this, use the Visibility setting in the Component Configuration pane. Select Only Show When and enter an expression in the Expression Editor. ● For example, imagine that you want to display a Comments field if a vehicle’s mileage is above 150,000 miles. You can enter the expression ri!vehicle[recordType!AX Vehicle.fields.vehicleMileage] > 150000. ● This expression determines whether the Comments component is displayed on the interface. When set to false, the component is hidden and not evaluated. The default is set to true."

I have the following in

How ever I get the following message when I try this tip.

Could not display interface. Please check definition and inputs. Interface Definition: Expression evaluation error at function a!paragraphField [line 156]: Cannot compare incompatible operands of type Null and type Number (Integer).

The reference application in community does not have this tip in it so its hard to see why and I don't fully understand why following the tip is not working correctly. 

Any comments on how to fix it would be appreciated. 

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