您必须将<models>包裹在<global>中，就像这样:

You must wrap <models> in <global>, just like this :

<global>
    <models>
        <firstmodule>
            <class>Ts_Firstmodule_Model</class>
        </firstmodule>
    </models>
</global>

不要犹豫，看看更简单的核心模块(例如GoogleAnalytics)的来源，看看它们是如何完成的，并了解其背后的逻辑.

Don't hesitate to take a look at the source of the simpler core modules (eg, GoogleAnalytics), to see how they're done and understand the logic behind it.