Admin Layout - Handle not picking up?

Question

I'm having issues getting a layout update to be picked up for a custom page in the admin. I did a handle dump on the page, and found the handle I expected:

adminhtml_salestracking_scripts_edit

I also have the following in my config.xml, to define the layout file:

<adminhtml>
    <layout>
        <updates>
            <salestracking>
                <file>company/salestracking.xml</file>
            </salestracking>
        </updates>
    </layout>
</adminhtml>

Then in app/design/adminhtml/default/default/layout/company/salestracking.xml:

<layout>
    <adminhtml_salestracking_scripts_edit>
        <reference name="head">
            <action method="addItem"><type>skin_js</type><name>company/js/base64.js</name></action>
        </reference>
    </adminhtml_salestracking_scripts_edit>
</layout>

The file exists in skin/adminhtml/default/default/company/js/base64.js.

I've done similar things in other modules before (and compared to find the same structure), but for some reason my admin page seems to just refuse to pick up the addition. It's also not trying to include a 404'd file or anything like that - there's simply no head line for it. Is there anything I'm missing?