How can I add a missing PyQt5 modules on Raspberry Pi

I am using PyQt5 version 5.7, python 3.5.3 and raspbian. My problem is that in my code some modules of PyQt5 get recognized and produce no error and some do.

The error I get: ImportError: cannot import name 'QMultimedia'

So why does QtCore/Widgets/Gui get reconized but not QMultimedia? Do I need to install some extra packages? Do I need to reinstall and do something special? This might be a trivial question but please help me.

Note: I also tried: from PyQt5 import QtMultimedia

import numpy as np
import sys
from PyQt5 import QtCore
from PyQt5 import QtWidgets
from PyQt5 import QtGui
from PyQt5 import QMultimedia
from PyQt5 import QCameraInfo
from PyQt5 import QVideoWidget
from PyQt5 import QMediaObject
from PyQt5.QtCore import pyqtSignal

class Camera():
    def iniCamera():
        cam = QCamera()
        caminfo = QCameraInfo(cam)
        print (caminfo.description)

        if caminfo.isNull() != True:
           cam = QCamera(caminfo.deviceName())
           print (caminfo.description)

if __name__ == '__main__':

    iniCamera()