WHMCS/Prve debug connection issue

[slrslr]

Hello,

when i add new Prve server in WHMCS 6.3.2 / Products / Servers, save and test connection it says "FAILED:".

How can i please debug the reason why it fails? My WHMCS is hosted on cPanel + Apache server.
In PVE v. 5.0-23 /var/log/pveproxy/access.log i can not find any related access.

I added line
error_reporting(E_ALL);
into this module files and found this error line:

PHP Notice: Undefined variable: success in /home/myusername/public_html/modules/servers/prve/prve.php on line 234

in /admin/error_log file. Here is the /modules/servers/prve/prve.php on line 234 :

function prve_TestConnection(array $params)
{
try {
// Call the service's connection test function.
$serverip = $params["serverip"];
$serverusername = $params["serverusername"];
$serverpassword = $params["serverpassword"];
$proxmox=new PVE2_API($serverip, $serverusername, "pam", $serverpassword);
if ($proxmox->login())
$success = true;
$errorMsg = '';
} catch (Exception $e) {
// Record the error in WHMCS's module log.
logModuleCall(
'provisioningmodule',
FUNCTION,
$params,
$e->getMessage(),
$e->getTraceAsString()
);
$success = false;
$errorMsg = $e->getMessage();
}
return array(
'success' => $success,
'error' => $errorMsg,
);
}

230 line is: $success = false;

Please kindly let me know if You need further information? Thank you