Troubleshooting observation in CQL

patientstuff.json

 {
    "fullUrl": "urn:uuid:b04ccc37-bc08-d37e-5b67-746a8d65aa14",
    "resource": {
      "resourceType": "Observation",
      "id": "b04ccc37-bc08-d37e-5b67-746a8d65aa14",
      "meta": {
        "profile": [ "http://hl7.org/fhir/us/core/StructureDefinition/us-core-observation-lab" ]
      },
      "status": "final",
      "category": [ {
        "coding": [ {
          "system": "http://terminology.hl7.org/CodeSystem/observation-category",
          "code": "laboratory",
          "display": "laboratory"
        } ]
      } ],
      "code": {
        "coding": [ {
          "system": "http://loinc.org",
          "code": "75622-1",
          "display": "HIV 1 and 2 tests - Meaningful Use set"
        } ],
        "text": "HIV 1 and 2 tests - Meaningful Use set"
      },
      "subject": {
        "reference": "urn:uuid:0ae954fa-eff8-0d38-c840-3af401abc9fd"
      },
      "encounter": {
        "reference": "urn:uuid:e4e11f0b-4e2e-4005-9005-d6552de634df"
      },
      "effectiveDateTime": "1993-09-11T11:01:17-04:00",
      "issued": "1993-09-11T11:01:17.230-04:00",
      "valueCodeableConcept": {
        "coding": [ {
          "system": "http://snomed.info/sct",
          "code": "165816005",
          "display": "HIV Positive"
        } ],
        "text": "HIV Positive"
      }
    },
    "request": {
      "method": "POST",
      "url": "Observation"
    }
  },

somestuff.cql

library HIVIndicators version '0.1.0'

using FHIR version '4.0.1'

include FHIRHelpers version '4.0.1'
include FHIRCommon called FC

// SNOMED-CT, International Edition
codesystem "SNOMED-CT": 'http://snomed.info/sct' version 'http://snomed.info/sct/900000000000207008'

// LOINC, 2.63+
codesystem "LOINC": 'http://loinc.org'

// HIV Test Results
code "HIV Negative": '165815009' from "SNOMED-CT" display 'HIV Negative'
code "HIV Positive": '165816005' from "SNOMED-CT" display 'HIV Positive'
code "HIV 1 and 2 tests - Meaningful Use set": '75622-1' from "LOINC" display 'HIV 1 and 2 tests - Meaningful Use set'

context Patient

define "HIV Positive Observation":
  [Observation: "HIV 1 and 2 tests - Meaningful Use set"] O
    where O.value = 'HIV Positive'

define "HIV Negative Observation":
  [Observation: "HIV 1 and 2 tests - Meaningful Use set"] O
    where O.value = 'HIV Negative'

define "Is HIV Positive":
  exists ("HIV Positive Observation")

define "Is HIV Negative":
  exists ("HIV Negative Observation")

define "Sex": Patient.gender