Created question in FIWARE Q/A platform on 08-09-2017 at 11:09
Please, ANSWER this question AT https://stackoverflow.com/questions/46112683/error-get-empty-value-when-retriving-data-from-sth-comet

Question:
Error get empty value when retriving data from sth-comet

Description:
First i register service using this script

curl -H "Content-type: application/json" -H "Fiware-Service:
cairoUniversity" -H "Fiware-ServicePath: /FCI/ICDL" \
http://X.X.X.X:4041/iot/services -d '{ "services": [

] }'

then i register device using this

curl http://X.X.X.X:4041/iot/devices \ -H "Content-type:
application/json" -H "Fiware-Service:cairoUniversity" -H
"Fiware-ServicePath: /FCI/ICDL" \ -d '{ "devices": [
{
"device_id": "smartmeter2",
"entity_name": "ICDL2",
"entity_type": "Camps",
"protocol": "PDI-IoTA-UltraLight",
"timezone": "Europe/Madrid",
"attributes": [

]
} ] }'

then i make subscription to orion

curl -X POST -H "Content-Type: application/json" -H "Accept:
application/json" -H "Fiware-Service: cairoUniversity" \
-H "Fiware-ServicePath: /FCI/ICDL" -H "Cache-Control: no-cache" -d '{
"entities": [

],
> "attributes": [
"Conscemption"
],
"reference": "http://X.X.X.X:8666/notify",
"duration": "P1M",
"notifyConditions": [

] }' "http://X.X.X.X:1026/v1/subscribeContext" }

after that i send observation

curl "http://X.X.X.X:7896/iot/d?k=api1&i=smartmeter2" -d 'c|47' -H
"Content-type: text/plain"

and finally retrieve data from sth

curl -X GET \
'http://X.X.X.X:8666/STH/v1/contextEntities/type/Camps/id/ICDL/attributes/Conscemption?aggrMethod=min&aggrPeriod=day&dateFrom=2015-01-28T00%3A00%3A00&dateTo=2018-01-01T23%3A59%3A59'
\ -H 'accept: application/json' \ -H 'cache-control: no-cache' \
-H 'content-type: application/json' \ -H 'fiware-service: cairoUniversity' \ -H 'fiware-servicepath: /FCI/ICDL' | python
-mjson.tool }

i got this respones

"contextResponses": [
{
"contextElement": {
"attributes": [

],
"id": "ICDL",
"isPattern": false,
"type": "Camps"
},
"statusCode":

}
]

and this the logs

sth-comet | time=2017-09-04T14:26:44.782Z | lvl=INFO | corr=n/a |
trans=n/a | op=OPER_STH_SERVER_LOG | from=n/a | srv=n/a | subsrv=n/a |
comp=STH | msg=Everything OK, 0 requests attended in the last 60s
interval sth-comet | time=2017-09-04T14:27:44.787Z | lvl=INFO |
corr=n/a | trans=n/a | op=OPER_STH_SERVER_LOG | from=n/a | srv=n/a |
subsrv=n/a | comp=STH | msg=Everything OK, 0 requests attended in the
last 60s interval

sth-comet | time=2017-09-04T14:27:52.834Z | lvl=WARN |
corr=99577e81-bbd4-4130-95f6-a9d029f84db0 |
trans=99577e81-bbd4-4130-95f6-a9d029f84db0 | op=OPER_STH_GET |
from=n/a | srv=cairoUniversity | subsrv=/FCI/ICDL | comp=STH |

> msg=Error when getting the aggregated data collection for retrieval
(the collection may not exist)

sth-comet | time=2017-09-04T14:28:44.792Z | lvl=INFO | corr=n/a |
trans=n/a | op=OPER_STH_SERVER_LOG | from=n/a | srv=n/a | subsrv=n/a |
comp=STH | msg=Everything OK, 0 requests attended in the last 60s
interval sth-comet | time=2017-09-04T14:29:44.797Z | lvl=INFO |
corr=n/a | trans=n/a | op=OPER_STH_SERVER_LOG | from=n/a | srv=n/a |
subsrv=n/a | comp=STH | msg=Everything OK, 0 requests attended in the
last 60s interval sth-comet | time=2017-09-04T14:30:44.805Z |
lvl=INFO | corr=n/a | trans=n/a | op=OPER_STH_SERVER_LOG | from=n/a |
srv=n/a | subsrv=n/a | comp=STH | msg=Everything OK, 0 requests
attended in the last 60s interval sth-comet |
time=2017-09-04T14:31:44.811Z | lvl=INFO | corr=n/a | trans=n/a |
op=OPER_STH_SERVER_LOG | from=n/a | srv=n/a | subsrv=n/a | comp=STH |
msg=Everything OK, 0 requests attended in the last 60s interval

What may case this problem and how solve it