Magento: Referencing a custom block does not work
I'm trying to reference a block from an other custom module to add a child block via layout file but it does not work.

The first layout file contains

    <catalog_product_view>
    	<reference name="content">
    		<block type="core/template" name="tabcontainer" as="tabcontainer"
    			template="store/tabcontainer.phtml" >
    			<block type="catalog/product_list_related" name="kitparts"
    				template="store/product/kitparts.phtml"/>
    		</block>
    	</reference>
    </catalog_product_view>

and in the second one I try to reference the `tabcontainer` block 

    <catalog_product_view>
    	<reference name="tabcontainer">
    		<block type="productshippinginfo/productshipping" name="productshippinginfo"
    			template="productshippinginfo/productshipping.phtml" after="kitparts"/>
    	</reference>
    </catalog_product_view>

but the `productshippinginfo` block is not displayed while it is definitely included in the layout (using Alan Storm's layoutviewer plugin). If I reference `content` it is displayed.

What is wrong? Isn't it possible to add a child to a custom block from a custom extension?

Thanks for your help!

(I'm using Magento 1.6.1.0)
Magento: Referencing a custom block does not work
===

I'm trying to reference a block from an other custom module to add a child block via layout file but it does not work.

The first layout file contains

    <catalog_product_view>
    	<reference name="content">
    		<block type="core/template" name="tabcontainer" as="tabcontainer"
    			template="store/tabcontainer.phtml" >
    			<block type="catalog/product_list_related" name="kitparts"
    				template="store/product/kitparts.phtml"/>
    		</block>
    	</reference>
    </catalog_product_view>

and in the second one I try to reference the `tabcontainer` block 

    <catalog_product_view>
    	<reference name="tabcontainer">
    		<block type="productshippinginfo/productshipping" name="productshippinginfo"
    			template="productshippinginfo/productshipping.phtml" after="kitparts"/>
    	</reference>
    </catalog_product_view>

but the `productshippinginfo` block is not displayed while it is definitely included in the layout (using Alan Storm's layoutviewer plugin). If I reference `content` it is displayed.

What is wrong? Isn't it possible to add a child to a custom block from a custom extension?

Thanks for your help!

(I'm using Magento 1.6.1.0)