Issue with overrides. Is this because the field is a bdp and not BBG about pdblp HOT 5 CLOSED

DEBUG:root:Sending Request:
 HistoricalDataRequest = {
    securities[] = {
        "SPY US EQUITY"
    }
    fields[] = {
        "SP_VOL_SURF_MID"
    }
    startDate = "20150629"
    endDate = "20150630"
    overrides[] = {
    }
}

DEBUG:root:Message Received:
 HistoricalDataResponse = {
    securityData = {
        security = "SPY US EQUITY"
        eidData[] = {
        }
        sequenceNumber = 0
        fieldExceptions[] = {
            fieldExceptions = {
                fieldId = "SP_VOL_SURF_MID"
                errorInfo = {
                    source = "236::bbdbh1"
                    code = 1
                    category = "BAD_FLD"
                    message = "Not valid historical field"
                    subcategory = "NOT_APPLICABLE_TO_HIST_DATA"
                }
            }
        }
        fieldData[] = {
        }
    }
}

DEBUG:root:Sending Request:
 ReferenceDataRequest = {
    securities[] = {
        "SPY US EQUITY"
    }
    fields[] = {
        "SP_VOL_SURF_MID"
    }
    overrides[] = {
    }
}

DEBUG:root:Message Received:
 ReferenceDataResponse = {
    securityData[] = {
        securityData = {
            security = "SPY US EQUITY"
            eidData[] = {
            }
            fieldExceptions[] = {
            }
            sequenceNumber = 0
            fieldData = {
            }
        }
    }
}

 ReferenceDataRequest = {
    securities[] = {
        "SPY US EQUITY"
    }
    fields[] = {
        "SP_VOL_SURF_MID"
    }
    overrides[] = {
        overrides = {
            fieldId = "REFERENCE_DATE"
            value = "20170525"
        }
        overrides = {
            fieldId = "VOL_SURF_EXPIRY_OVR"
            value = "20180119"
        }
        overrides = {
            fieldId = "VOL_SURF_STRIKE_OVR"
            value = "200"
        }
    }
}

DEBUG:root:Message Received:
 ReferenceDataResponse = {
    securityData[] = {
        securityData = {
            security = "SPY US EQUITY"
            eidData[] = {
            }
            fieldExceptions[] = {
            }
            sequenceNumber = 0
            fieldData = {
                SP_VOL_SURF_MID = 19.261268
            }
        }
    }
}