Why second select box is not populating at first time?

Hi all,
Can u saw this page once, to understand my problem…
http://www.rfcables.org/cable_design1.php
In this page i used jquery to load the form data at the time of page loading…
I want to select radio button of ‘select cable’.
Then i want to select a category, usally it shows another select box based on the first select…
But the problem is,
When i select the item from the select box under ‘select cable’, it wont show the next select box at, first time… why?
but on the second time, it is showing…

Can any one make it the problem…
and give me the solution to solve this problem…

Thanking you…