Magento products are not displayed in front end home page

Magento products are not displayed in front end home page

I have installed a theme for magento store in order to display the
products which i have added recently i have written this code in the
content of the home page :
{{block type="catalog/product_list" name="home.catalog.product.list"
alias="products_homepage" template="catalog/product/list.phtml"}}
using this it is displaying the preloaded products of theme , to display
the products of my category i changed this to :
{{block type="catalog/product_list" category_id="39"
template="catalog/product/list.phtml"}}
But now it is giving me an error like :
There are no products matching the selection.
and same error it is showing when a category is clicked in the navigation
bar.