Unable to post to Phonograph , getting readonly error

When i am trying to update a row in Phonograph i am getting the following error.

q_update_phonograph threw the following error: {
  "errorCode": "INVALID_ARGUMENT",
  "errorName": "Phonograph2:ReadOnlyTables",
  "errorInstanceId": "instanceId",
  "parameters": {
    "tableRids": "[phonograph rid]",
    "dataInputLocatorRids": "[foundry dataset rid]"
  }
}

This is what i am passing in the Table Storage Service Post Event

{
  "extractors": {
    "result": "$"
  },
  "headers": {},
  "method": "POST",
  "path": "storage/edits/tables/{tableRid}/events",
  "pathParams": {
    "tableRid": "phonograph rid"
  },
  "queryParams": {},
  "bodyJson": {
    "primaryKey": {
      "uniq_field": "uniq_fieldValue"
    },
    "payload": {
      "type": "rowModified",
      "rowModified": {
        "columns": {
          "Comments": "Test Data"
        }
      }
    }
  }
}

First the write back dataset needs to be created, then this issue will be resolved. Thank you nicornk