Why is PreSaveAction not working and not firing in my SharePoint 2013 NewDocSet.aspx page?

Dear SharePoint Experts,

Please help.

Why is PreSaveAction not firing on my NewDocSet.aspx page that is based on a custom Content Type?

--- In my SiteAssets folder, I have these files...

jquery.js (which is jQuery JavaScript Library v1.11.1)

CustomScripts.js (which is my custom JS file)

--- On my Master Page, I have this...

...blah...

<SharePoint:CustomJSUrl runat="server" />

<!-- NOTE. 2014-11-17. MFK. New links. Begin -->

<SharePoint:ScriptLink language="javascript" name="~site/siteassets/jquery.js" runat="server" OnDemand="False" LoadAfterUI="True" />

<SharePoint:ScriptLink language="javascript" name="~site/siteassets/CustomScripts.js" runat="server" OnDemand="False" LoadAfterUI="True" />

<!-- NOTE. 2014-11-17. MFK. New links. End -->

<SharePoint:SoapDiscoveryLink runat="server" />

...blah...

--- In CustomScripts.js I have this...

alert('Found me.'); //Does show.

function PreSaveAction()
{
 alert("Found PreSaveAction."); //Does NOT show.

 return false;
} 

--- What do you think?

Please advise.

Thanks.

-- Mark Kamoski