Regist the domain Return:error->400

When i use versio API and php CURL, the service return 400,but the postDate mabe not worng
I refer to
https://www.versio.nl/RESTapidoc/#api-Domains-List
But the domain name registration has not been completed
my demo

<?php
$post_a = array(
'contact_id'=>529254,
'years'=>1
);
$curl = curl_init();
curl_setopt($curl,CURLOPT_URL,'https://www.versio.nl/api/v1/domains/letone.be');
curl_setopt($curl,CURLOPT_RETURNTRANSFER,true);
curl_setopt($curl,CURLOPT_HTTPAUTH,CURLAUTH_BASIC);
curl_setopt($curl,CURLOPT_USERPWD,"myaccout:mypwd");
curl_setopt($curl,CURLOPT_SSL_VERIFYPEER,false);
curl_setopt($curl,CURLOPT_FOLLOWLOCATION,1);
curl_setopt($curl, CURLOPT_POST, 1);
curl_setopt($curl, CURLOPT_POSTFIELDS, $post_a);

$response = curl_exec($curl);
$data = json_decode($response);
print_r($data);


//the first run,and the return
//stdClass Object( [error] => stdClass Object ( [code] => 400 [message] => ObjectInvalid|Invalid years ameter )

//the The next run result has always been
//stdClass Object ( [error] => stdClass Object ( [code] => 400 [message] => ObjectNotAllowed|Domain registration already requested ) )

I was able to reproduce this, seems like versio does not like bad requests and just denies you from registering it again?

I have the same problem. I am trying to register a domain name using the API and I get the same errors:

Error after first run:
stdClass Object( [error] => stdClass Object ( [code] => 400 [message] => ObjectInvalid|Invalid years parameter )

Error after second run:
stdClass Object ( [error] => stdClass Object ( [code] => 400 [message] => ObjectNotAllowed|Domain registration already requested ) )

Please not that I tried this with various domain names and they all give this error.
Also, I tried both 1 and 2 as years parameter.

Can someone explain what is wrong? Here is my code (very similar):

<?php
$login="my_email_to_login_on_versio";
$password="my_password_to_login_on_versio";

$post = [
'domain' => 'example.nl',
'contact_id' => my_customer_number,
'years' => 1,
];
$curl = curl_init();
curl_setopt($curl, CURLOPT_URL,'https://www.versio.nl/api/v1/domains/example.nl');
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl, CURLOPT_HTTPAUTH, CURLAUTH_BASIC);
curl_setopt($curl, CURLOPT_USERPWD, "$login:$password");
curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($curl, CURLOPT_POSTFIELDS, $post);
curl_setopt($curl, CURLOPT_CUSTOMREQUEST, "POST");
curl_setopt($curl, CURLOPT_FOLLOWLOCATION, 1);
$response = curl_exec($curl);
$data = json_decode($response);
print_r($data);

/* Get the redirection URL */
$redirectURL = curl_getinfo($curl,CURLINFO_EFFECTIVE_URL );
$httpCode = curl_getinfo($curl, CURLINFO_HTTP_CODE);
?>