When you join Digital Throttle, you may provide us a "default creative" to serve when we don't use an impression you've provided us. Two main reasons we won't be able to fill your impression: (1) Your "Reserve Price" is too high to attract 100% fill (your reserve price is the minimum CPM you'll accept) or (2) We just don't have an ad to display due to the geography or nature of the impression.
For these "unsold" impressions, you will want a default creative to display. If you don't supply a default creative, we will display a free public service ad (PSA). If you currently use DFP for Small Business and want us to "passback" the unsold impression to DFP, please see the following link to the DFP Help Site:
Update: Use this site for your DFP Passbacks
We've seen a vast improvement in Passback speed and accuracy through when you use this semi-secret site setup to generate passback tags to your DFP ad units. http://dfpgpt.appspot.com/.
The tool will kick back a tag that looks like this:
<!-- Beginning PassBack for Ad unit some_adunit_name ### size: [[728,90]] -->
<!-- End Passback -->
See this image on the fields to select. But warning! Be sure to check these tags first on an HTML preview system like http://htmledit.squarefree.com/ to ensure an ad is displaying: