Cant get the collapse button to work on portfolio page menu

Hey guys im trying to get this menu up and running for my portfolio page but the button to allow you to view the menu in small screen is not dropping down. I have looked over my code and cant figure out why not so figured i would ask you guys. Here is the link to the Codepen

Try adding the following below your first <script></script>

<script src=""></script>

You need the bootstrap js file above for the small screen drop-down to work.

Cool it works now, thank you for that. Been trying to figure it out over the last day.