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Hi Steven, probably you modified the file related.phtml (appdesignfrontendbasedefaulttemplatecatalogproductlistrelated.phtml)
This file is from the Magento base, so it's important to not change it. Check if you have this line in your catalog.xml :
<block type="catalog/product_list_related" name="catalog.product.related" before="-" template="catalog/product/list/related.phtml"/>
We can send you the file related.phtml if you want.