Script for neagtive Inventory adjustment

Hi All,

I am trying to create an inventory Adjustment using suiteScript 2.1 While trying to set the "adjustqtby" as a negative value. It rejects the input. With the following error please let me know why this error occurs?

Error message "type":"error.SuiteScriptError","name":"INVALID_FLD_VALUE","message":"Value -1.0 outside of valid min/max range for field adjustqtyby"

Script is below

let createInventoryAdjustment = (siteId)=> {

try {

var inventoryAdjustmentRecord = record.create({

type: record.Type.INVENTORY_TRANSFER,

isDynamic: true

});

inventoryAdjustmentRecord.setValue("account",accountId)

let index = 0;

let currentInventoryData = getSerielNumbers(siteId);

let itemVsSerialNo = currentInventoryData.results;

let itemsVsQty = currentInventoryData.itemsVsQty;

for (var key in itemVsSerialNo) {