Expression rule Query Error

Hi, I'm doing the activity of the course, but I got a problem with this query: 

a!queryRecordType(
recordType: 'recordType!{058be2d0-0acb-453f-93ac-4c9f650cf004}Vehicle',
fields: a!aggregationFields(
groupings: a!grouping(
field: Vehicle.make,
alias: "Vehiclemake"
),
measures: a!measure(
field: Vehicle.make ,
function: "COUNT",
alias: "count"
)
),
pagingInfo: a!pagingInfo(
startIndex: 1,
batchSize: 100
)
) .data

when I tried to test the rule I got this error: Expression evaluation error at function a!aggregationFields [line 3]: Could not find variable 'Vehicle'

I followed every single step in the exercise So, I don't understand what's the wrong here. Can anyone tell me what's the wrong??