问用POST提交,提示缺少Version？

代码:

$data = [

'Action' => 'TextToVoice',

'Version' => '2017-03-12',

'Region' => 'ap-beijing',

'Text' => '你好',

'SessionId' => $this->guid(),

'Volume' => 5,

'Speed' => 0,

'ProjectId' => 0,

'ModelType' => 1,

'VoiceType' => 0,

'PrimaryLanguage' => 1,

'SampleRate' => 16000,

'Codec' => 'mp3',

'Signature' => $sgin

];

header('Content-Type: application/x-www-form-urlencoded');

$result = post_data('https://tts.tencentcloudapi.com',$data);

返回结果

"{"Response":{"Error":{"Code":"MissingParameter","Message":"The request is missing a required parameter `Version`."},"RequestId":"d04d479d-e6a1-49ef-bf09-badc9ceaf00b"}}"