signature 生成的跟工具上测试的是一样的，为什么还是签名错误呢

lingka:function(){

wx.request({

url: app.d.ceshiUrl+’/Api/Api/suiji’,

method: ‘post’,

data: {

},

header: {

‘Content-Type’: ‘application/x-www-form-urlencoded’

},

success: function (res) {

console.log(res)

var time = JSON.stringify(res.data.time);

var str = JSON.stringify(res.data.success);

console.log(str)

console.log(time)

wx.addCard({

cardList: [

{

cardId: ‘pRYCp0yeF36-CY1CxF6eQq5BdBnI’,

cardExt: '{“code”: “”, “openid”:"", “timestamp”: ’ + time + ‘, “signature”:’ + str+ ‘}’

}

],

success: function (res) {

console.log(res) // 卡券添加结果

}

})

}

})

}

 前端代码哪里错了吗