If a rich content creative doesn't link to the proper destination URL, first see whether the destination URL works without a click macro.
If the destination URL works, make sure you've inserted the click macro in the proper location and that you're using the proper version of the macro:
For most third-party tags, you will use the standard click macro. Click Insert click macro to insert
%%CLICK_URL_UNESC%%into your tag.
If the clickthrough URL of your third-party tag contains special characters (e.g. '&', '?', '%'), click Insert double-escaped click macro to insert
%%CLICK_URL_ESC_ESC%%into your tag.
If a particular network or rich content creative doesn't support clickthrough tracking, DFP Small Business can serve, but not track, those ads.