Note: An ad won't be shown on G's partner sites until it's reviewed. #6, often comes into play with sudden disappearances on partner sites.
1. Budget Issue. Far and away the #1 reason. If it requires $100 a day for your ads to show all day, and your budget is $50, then your ads will only be shown for 50% of the searches for your term.
1a. Budget Issue #2. You got a lot of clicks in the morning/afternoon, and your budget ran out earlier in the day than G expected, so your ad won't be shown at all in the evening.
2. It's being displayed - look again. People are use to scanning the right side of the screen for ads, and often miss when their ad is in the premium position. Check the 2nd and 3rd pages, until the first ad is redisplayed, to see if you're listed in a later page.
3. Negative keywords. Often we make lists of 100s of negative keywords to further define traffic. If you input one of these negative words, your ad won't be displayed.
4. Sensitive keywords. It's a new ad with a word that is flagged by G as a 'sensitive' KW. These rules for what is sensitive is not posted by G, but they maintain a list and auto flag some KWs.
5. 100k Impressions. Congrats your ad was shown this many times. G reviews ads when they hit this benchmark, and might suspend an ad for a couple days while it's rereviewed.
6. Changed Ad Copy. Cardinal rule, if the ad isn't disallowed, don't change it - make a new one instead, and delete the old one once the new one is approved. When you change anything on an ad, and G means any little thing, it's considered a new ad and must be rereviewed.
7. Unpaid account. If the credit card or debit card is rejected, and for some reason the funds can't be replinished by G, the ads are suspended until the account is paid.
8. Geo Targeting. These ads are only displayed if you live in the target region. Even if you live in the target region, G can't always determine your location, and may serve you national ads.
9. Countries. Same as #7, but easier to add the G extension to the search URL to actually see your ad.
10. Disabled due to low CTR. Ad ad must meet a minimum requirement to be displayed. If it falls below this for the last 1000 impressions, it will be suspended.
11. Deleted and readded a low preforming KW. If you delete and make a new campaign for a disallowed KW, your KW is still flagged as underpreforming, and you must follow the appropriate steps to get the flag removed.
12. New account. When an account is created, it takes a few hours (possibly days on weekends) for your ad to start showing. G does not send out emails when ads are approved or reviewed, so it could go live at any moment, but if you fall under the 'sensitive KW' (see #4 above), it will take longer.
That's all the reasons I can think of on only my 3rd cup of coffee. I'm sure I missed a few, so please add any other reasons ads aren't displayed.
I can't think of any new line items, but I did have a couple of small additions, as noted below:
1. Budget Issue. Far and away the #1 reason. If it requires $100 a day for your ads to show all day, and your budget is $50, then your ads will only be shown for 50% of the searches for your term.
Bingo! You are right on the money. This is the number one cause of ads not appearing, by far, in my experience. To this, I wanted to add that confusion seems to result when advertisers look at how much they have spent so far in the day, when they want to evaluate if budget is the reason for the non-appearance of their ad.
Actually, this is not the best thing to check.
It is much more important to check the "Recommended Budget", and see how it compares to your actual budget. You can check this on the 'Edit Campaign Settings' page, which is available, per campaign, by clicking the 'Edit Campaign Settings' link near the top left of each campaign page.
11. Deleted and readded a low preforming KW. If you delete and make a new campaign for a disallowed KW, your KW is still flagged as underpreforming, and you must follow the appropriate steps to get the flag removed.
To this I'd like to add that it is very important to delete the keyword, everywhere it appears in your account before attempting to re-enter it. Note that this means you must also delete it within paused or deleted campaigns and Ad Groups. If you don't do this, the keyword will get only a very few impressions before being disabled again. This is because in the eyes of they system the keyword is actually still disabled.
For this reason, IMO, it is a very good practice to simply delete any disabled keyword immediately, as a matter of routine. Then if the keywords is important to you, consider using it again in a different (and more targeted) Ad Group.
AWA
To this I'd like to add that it is very important to delete the keyword, everywhere it appears in your account before attempting to re-enter it. Note that this means you must also delete it within paused or deleted campaigns and Ad Groups.
Thank you. That I didn't know, and is exactly what I've been looking for about deleted KWs.
I'd have never thought that a deleted campaign would still be considered part of the system.
If for example you search from Europe with the Google toolbar (set to google.com) or you search with the "Google.com in English" from Europe you could see Froogle listings on top and correctly geo/language targeted adwords on the right. Once you go to Froogle the ads differ (and probably?) only show US? targetted ads?
I'm probably confused, but it seems like a double geo-targetting problem.
(imagine showing only/mainly European vendors top three Froogle listed with EURO pricing to US-searchers and then offering Americans European targetted Adwords once clicking into Froogle..)
Affiliate Policy/Multiple Domain Rule
Google has restricted how many ads can be shown for one page at a single time. If you and other affiliates and the merchant are bidding on the same keywords, all of the ads may not show.
Two WebmasterWorld discussions on the policy:
[webmasterworld.com...]
[webmasterworld.com...]
Google Newsletter about the policy:
[adwords.google.com...]
Google Ad Diagnostic Tool
Google has a tool, which can help one determine why an ad isn't showing:
You can access the tool via the following steps:Log into your AdWords account.
Click Tools beneath the Campaign Management tab.
Click Ads Diagnostic Tool.
Enter information for either Option 1 or Option 2:
From: Google Info on the diagnostic tool [adwords.google.com]
WebmasterWorld Discussion on the Ad Diagnostic Tool:
[webmasterworld.com...]