"Must provide a field name for parameter" error message

[nikitanaresh]

Hi, I’m trying to create a simple parameter to choose between 2 dimensions to breakdown a view. I’ve copied the syntax exactly from the Looker docs, but keep getting an error saying that the “parameter’ needs a field name:

parameter: regiondrilldown {
    type: unquoted
    allowed_value: {value: "Country"}
    allowed_value: {value: "State"}
    allowed_value: {value: "City"}
  }

  dimension: geo_breakdown {
    type: string
    label_from_parameter: regiondrilldown
    sql:
      case
        when {% parameter ${regiondrilldown} %} = 'Country' Then ${country}
        when {% parameter ${regiondrilldown} %} = 'State' then ${state}
        when {% parameter ${regiondrilldown} %} = 'City' then ${city}
      end ;;
  }