Somtime works, somtimes SoapFault Internal Server Error

[TechNov]

Hi i use this paacket like describe in docimentation.
But sometime my request works fine, somtile it fail with this eror: SoapFault Internal Server Error without change anything

`$this->soapWrapper->add('Currency', function ($service) {
$service
->wsdl('http://currencyconverter.kowabunga.net/converter.asmx?WSDL')
->trace(true)
->options(['user_agent'=>'PHPSoapClient']) // Indispensable pour le PHP
->classmap([
GetConversionAmount::class,
GetConversionAmountResponse::class,
]);
});

// With classmap
$response = $this->soapWrapper->call('Currency.GetConversionAmount', [
  new GetConversionAmount('USD', 'EUR', '2014-06-05', '1000')
]);`

Help please;