Please allow up to 3 hours for ads to start displaying correctly before contacting Google DFP customer support. If it has been longer than 3 hours, you can reach Google support here: https://support.google.com/dfp_premium/?hl=en#topic=28132&contact=1
The Blog List Ad Code feature lets you display ads within your blog lists. Only users with advertising permissions can access this setting. Ads will appear at the full width of the blog list widget; the height will vary based on your ad code.
If you have any questions or need further assistance, please contact SoCast Support.