SPServices.SPCascadeDropdowns in SharePoint 2013 Online

I am using the .SPServices.SPCascadeDropdowns JavaScript in a SharePoint site. When I implement this in the root site collection site, everything works fine.

I also have these two references in the Master page:

         <script type="text/javascript" src="//code.jquery.com/jquery-1.11.2.min.js"></script>
         <script type="text/javascript"
            src="//cdnjs.cloudflare.com/ajax/libs/jquery.SPServices/2014.02/jquery.SPServices.min.js"></script>

However, when I try to implement it in a team (sub) site, the JavaScript stops working because it appears that it has to be located at the root site collection level.

When I add the script directly to the master page, then the forms in the team (sub) site works perfectly.

However, I don't want to have to add these scripts to the master page so I created a link to the .js file

        <script type="text/javascript" src="/SiteAssets/scripts/customscripts.js"></script>

But when I do this, the script stops working.

Can any body give me any indication what I am doing wrong. I believe it is a path issue, but I cannot figure out what needs to be done.

Thanks.