CURL之后PHP中的XML解析错误

I have obtained such a response after executing one curl request.

<?xml version="1.0" encoding="utf-8"?>
<mp_response>
<response_element>
<merchantid>
36573dkjdkjds3987398
</merchantid>
<orderid>
1
</orderid>
<responsecode>
23
</responsecode>
<description>
Transaction Payout Completed
</description>
</response_element>
</mp_response>

But when I use functions like

new SimpleXMLElement($xml_str);
simplexml_load_string($data)

etc. I get an error like

Start tag expected, '&lt;' not found

What should I do?

After closing curl use "simplexml_load_string($string)"
$string is a variable which stores curl_exec();
Then take a variable for retrieving data from the xml.
e.g.,

$data=simple_load_string($string);
$response=$data->response_element->merchantid;