Magento – how load block in controller

I use the following code to load a block in controller

$this->loadLayout();
      if ($this->getLayout()->getBlock('checkout.cart1')) {
        $cartlink =  $this->getLayout()->getBlock('checkout.cart1')->toHtml();
      }

1. Here the checkout.cart1 is block name.

2. My layout file code is

   <quickbuy_index_index>  
   <reference name="content">
   <block type="checkout/cart" name="checkout.cart1">
   <action method="setCartTemplate"><value>checkout/cart1.phtml</value></action>
   <action method="setEmptyTemplate"><value>checkout/cart/noItems.phtml</value></action>
             .
             .
             .
   </block>
   </reference>
   </quickbuy_index_index>
   

3. Here my tag is <quickbuy_index_index>

4. Now the controller code not load my block .
5. But When i put the layout code within <default> tag instead of <quickbuy_index_index> tag, the controller load the block. like this

<default>
<block type="checkout/cart" name="checkout.cart1">
<action method="setCartTemplate"><value>checkout/cart1.phtml</value></action>
<action method="setEmptyTemplate"><value>checkout/cart/noItems.phtml</value></action>
          .
          .
          .
</block>
</default>

6. How i load the block in controller from <quickbuy_index_index> tag.

7. My problem is, When i put a block in <default> tag, the controller load it.
   when i put a same block in url tag (<quickbuy_index_index>) the controller not load it.