Re: How can I add keywords to my PLA campaign and make them validate?
Hello Lloyd J, Welcome to the Community
A PLA campaign uses words from the product Titles or Descriptions to match the search terms.
The Keywords tab is ineded active in such a campaign,because it allows you to run non-PLA ads ( text ads) at the same time . For more information , please read the following :
Also from here : https://support.google.com/adwords/answer/2456103?hl=en
Understanding product targets and keywords
Instead of keywords, Product Listing Ads use product targets to determine when items in your Merchant Center account appear on a search results page. Defining keyword lists for proactive targeting won't have any effect on your Product Listing Ads or product targets at this time. However, you can use negative keywords to limit the searches for which your ads will show. Negative keywords can be applied at the ad group or campaign level."'
I hope this helps