Enabling httpcookies

I have a web sites in which I need to ssl enable cookies.   I looked up how to enable it and it seems straight foward.  add the statement <httpcookies httponlycookies="true" requiressl="true" /> to system web.  

I checked out the web.conf of one of the sites, and it's a really simple web.conf:

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<system.webServer>
<defaultDocument>
<files>
<add value="redacted.html" />
</files>
</defaultDocument>
</system.webServer>
</configuration>

So I added a system web section: 

<?xml version="1.0" encoding="UTF-8"?>
<configuration>

<system.web>
<httpcookies httponlycookies="true" requiressl="true" />
</system.web>
<system.webServer>
<defaultDocument>
<files>
<add value="redacted.html" />
</files>
</defaultDocument>
</system.webServer>
</configuration>

Restarted IIS and tested the website and when I tested I received the following message

Config source:

<system.web>
<httpcookies httponlycookies="true" requiressl="true" />
</system.web>

Config error The configuration section 'httpcookies' cannot be read because it is missing a section declaration.   

Can anyone advise?  The examples I've seen have not show any more section declaration then system.web is required to enable this and I'm not an IIS guy so I'm not sure where to look for a solution.

Thanks,