public function getCampaigns()
       {
       $requestUrl = "https://www.zohoapis.com/crm/v2/Campaigns?scope=ZohoCRM.modules.ALL";        

     

       $headers = array(

       " Authorization:Zoho-oauthtoken XXXXXXXXXXf6     

);

        $ch = curl_init();
        $ch = curl_init($requestUrl);
        curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

        $result = curl_exec($ch);
 But after executing the CURL I got the following response :-

{
    "code": "OAUTH_SCOPE_MISMATCH",
    "details": {},
    "message": "invalid oauth scope to access this URL",
    "status": "error"
}

How actually scope parameter should we passed in URL?

please help