[jQuery] watch window problems and ideas

[jQuery] watch window problems and ideas

I'm a newbie, using VS and firebug debuggers as I learn jQuery.
I find it very helpful to pause at various breakpoints and experiment with jQuery chains to see what works.
But I find that the results aren't always consistent. Especially in IE.
Examples:
<br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">$('li')          result is empty jQuery</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">$('LI')          result is jQuery with 9 elements</span>
<span style="font-family: courier new,monospace;">$('li').get()    result is array with 9 elements</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"></span>
Can anyone explain these inconsistencies?
Any warnings / suggestions about how to make the best use of the watch window?
Many thanks,
Ken