How to find the first direct child element of a div

Question

This should be easy but I am not able to do it.

I have a div element with id "LeftScrollableDiv" and I am trying to find the first child element under it:

$("#LeftScrollableDiv:first-child");  <div id="LeftScrollableDiv:first">    <table></table> </div> 

But the result is null. Any help??