Not able ro get lead data

Not able ro get lead data

Hi i want to get the zoho lead by using https://www.zohoapis.com/crm/v2/Leads by generating the accesstoken but
i got the respnse as

{

    "code": "OAUTH_SCOPE_MISMATCH",

    "details": {},

    "message": "invalid oauth scope to access this URL",

    "status": "error"

}


please help