Bad request

[Rajdev2011]

GuzzleHttp\Exception\ClientException #400
Client error: POST https://dev-ecomm.myshopify.com/admin/oauth/access_token resulted in a 400 Bad Request response: search

Iam using this package with the codeignetor framework .When iam trying to get the access token iam getting above issue .Below is my code

$api = new Api(array(
'api_key' => SHOPIFY['API_KEY'],
'api_secret' => SHOPIFY['API_SECRET'],
'myshopify_domain' => $this->request->getGet('shop')
));
$helper = $api->getOAuthHelper();

	$token = $helper->getAccessToken($_REQUEST['code']);

Please can you tell me what iam doing wrong