Problem with UDF Sending Using API

Problem with UDF Sending Using API

I'm unable to send UDF values using the REST API,

UDF Fields added see the attachment,

API Request Body:

{
  "request": {
    "subject": "subject",
    "description": "desc",
    "requester": {
      "id": "4503",
      "name": "API"
    },
    "udf_fields": {
      "udf_sline_301": "Ahmed ",
      "udf_long_302": 6082,
      "udf_sline_303": "+966"
    }
  }
}

API Response:

{
    "response_status": {
        "status_code": 4000,
        "messages": [
            {
                "status_code": 4001,
                "type": "failed",
                "message": "Invalid Input",
                "fields": [
                    "udf_sline_303",
                    "udf_sline_301",
                    "udf_long_302"
                ]
            }
        ],
        "status": "failed"
    }
}

Please help me to figure out why it won't work.
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