Ok, I found my problem. I am not sure what .order_by presents, but if I change 10 to 50 or comment the below line out, the main categories shows up on the tab.
Code:
{if $categories[cat_num].order_by lt 10}
So, if there are too many categories, the tab will be too wide. Can put the menu into two rows?
I am still trying two problems:
1. If I want to add an additional tab to the menu, the color change will not be right. For example, add below line to the tab_menu.tpl
<TD align="center" class="tabmenuitem" nowrap>
<span>Test</span>
</TD>
2. Once I click on a subcategory, the red color on the text of subcategroy will be kept. I guess it can be fixed by css file, but donot know how yet.
Thanks again.
Jeff