Why isn't my Online Advertising ad showing up on search engines?
Don't be concerned. Search Engines spread out ad views over the course of a day, so your ad won't automatically display every time you do a search. Once your daily budget is reached, your ad usually stops showing so you don't accrue additional costs. Consider increasing your budget if you want the ad to show more often.
Also, if you select a custom category, you need to allow three business days for your search campaign to begin.
For more information, see How do I know Search Engine Visibility Online Advertising is working?