How to properly add new child with children in xml - php

Question

An API returns the following, and I want to add another data record for testing purposes:
<?xml version="1.0" encoding="UTF-8" ?>
<API>
<code>0000</code>
<time>1549959757</time>
<data cnt="1">
<record>
<record>
<approval_idx>224833</approval_idx>
<reg_date>2019-02-12</reg_date>
<user_id>test</user_id>
<state1>10</state1>
<state2>03</state2>
<name>tester</name>
<e_id>3743</e_id>
<cname>test cname</cname>
<cId>3089</cId>
<loc>oh</loc>
</record>
</record>
</data>
</API>
I tried doing this
$utilApi = new libUtilApi($apiRequest);
$utilApi->request();
$resultAPI = $utilApi->response;
$resultAPI = simplexml_load_string($resultAPI);
$record = $resultAPI->addChild("record");
$record->addChild("approval_idx", "7546");
but the output look like this
<?xml version="1.0" encoding="UTF-8" ?>
<API>
<code>0000</code>
<time>1549959757</time>
<data cnt="1">
<record>
<record>
<approval_idx>224833</approval_idx>
<reg_date>2019-02-12</reg_date>
<user_id>test</user_id>
<state1>10</state1>
<state2>03</state2>
<name>tester</name>
<e_id>3743</e_id>
<cname>test cname</cname>
<cId>3089</cId>
<branch>oh</branch>
</record>
</record>
<record>
<approval_idx>7546</approval_idx>
<reg_date>2019-02-13</reg_date>
<user_id>test3</user_id>
<state1>75</state1>
<state2>09</state2>
<name>new test</name>
<e_id>7546</e_id>
<cname>Q1</cname>
<cId>325</cId>
<branch>oh</branch>
</record>
</data>
</API>
The added child is not going in right position, I tried
$record = $resultAPI->record[0]->addChild("record");
but it falls to an error like:
Call to a member function addChild() on null
-I just updated the code, yes the api is returning the proper format and data, its just that I can't make the addition of children on the right place