<tbody> vs. <table>

[lightnb]

I'm running into a problem where using <tbody> causes the header bar to malfuntion, while using <table> in it's place fixes the header bar, but causes other things to go wrong.

What is the difference between these two tags, and more importatly, what can i do to make one of them work right?

I've attached two screen shots showing the difference. The first uses <table>, the second, <tbody>.