I haven't used both jQuery's plugins before,
but after spying your page deep down,
I got this (focus on item quantity only):
The item quantity on top right of page, see line 137:
Code:
...(items: <span class="simpleCart_quantity"></span>)...
On the other hand,
what pasted into <div class="simpleCart_items" ></div> (line 130) is something like:
Code:
...<a href="javascript:;" onclick="simpleCart.items['c2'].decrement();">-</a>
</div>
<div class="itemQuantity">7</div>
<div class="itemincrement">
<a href="javascript:;" onclick="simpleCart.items['c2'].increment();">+</a>
</div>...
So, should the red classes have the same name?