Emulating traffic from gateway

I’m using Jmeter to emulate the traffic from Gateway in order to do a load balance test.
I’ve copied the real payload message using MQTT Explorer and trying to use it as payload in Jmeter.
When I do a request I’m receving 200 from Chirpstack server, seeing may payload message in MQTT Explorer but do not my message in application server and my integration is not being triggered.
I’ve started to test with identical payload to the one which receved from real gateway and then tried to play with fCnt (using bigger number) and uplinkID (using random sequence). Nothing helps.
Could you advice why app server does not recognize my messages from Jmeter?
Here is the sample message:
“applicationID”: “1”,
“applicationName”: “TestApp”,
“deviceName”: “ab00504”,
“devEUI”: “70b3d5ca5000fbc3”,
“rxInfo”: [
“gatewayID”: “c0ee40ffff29682e”,
“uplinkID”: “a8e97f69-f929-4331-9baf-616a12f51f98”,
“name”: “temporary”,
“rssi”: -63,
“loRaSNR”: 12,
“location”: {
“latitude”: 0,
“longitude”: 0,
“altitude”: 0
“txInfo”: {
“frequency”: 904500000,
“dr”: 1
“adr”: false,
“fCnt”: 561,
“fPort”: 2,
“data”: “CjQKJgofCiwKFwoRCgkKCAoGCgMKBQoBCf4J/wn5CfkJ9gn2CfQJ8QnrCecJ4gna”