Firebug not always expanding tree in HTML panel

[anderslinden]

When I right-click on an element inside the page and choose Inspect Element with Firebug most of time time I will come to the node in the HTML panel. Sometimes it will not expand and I have to inspect a nearby element instead.

Did I not "hit" an element? Did I do something wrong? This has been for a while so I start to suspect that I do not know how to use it properly.