JSON extract value from payload | issue in extraction

[sjm2000]

Dear Team

I have below JSON payload .

I wanted to extract paynumber as json variable.

i tried using "$.usefullFields.paynumber".

However the value is not getting extracted.

Do you have any ideas?, I am running out of luck. No idea why we have this strange behavior!! 🙂

{  
"usefull_val": "f243b5d507bc4c1a8e74b3c926390da468f5e161",
  "usefullFields": {
    "paynumber": "002022059182"
  },
  "customuser": {
    "timezone": "America/Los_Angeles"
  },
  "costomer_source": {
    "id": "e16e9a992d2f4044",
    "url": "http://example.com/e16e9a992d2f4044"
  }
}