I checked out your code in more detail: The problem is that "Linux & Unix" isn't a CriterionUserInterest, it's a Vertical<https://developers.google.com/adwords/api/docs/appendix/verticals>. This code's working for me in the sandbox:
$interestId = 736; //Linux & Unix $interest = new Vertical(); $interest->id = $interestId; $interest->path = array("Computers & Electronics", "Software", "Operating Systems", "Linux & Unix"); $campaignCriterion = new NegativeCampaignCriterion(); $campaignCriterion->campaignId = $campaignId; $campaignCriterion->criterion = $interest; $operations = array(); $operations[] = new CampaignCriterionOperation($campaignCriterion, 'ADD'); $campaignCriterionService->mutate($operations); Note that you also need to enter the category path, even though you've already entered an id. -- =~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~ Also find us on our blog and discussion group: http://adwordsapi.blogspot.com http://groups.google.com/group/adwords-api =~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~ You received this message because you are subscribed to the Google Groups "AdWords API Forum" group. To post to this group, send email to adwords-api@googlegroups.com To unsubscribe from this group, send email to adwords-api+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/adwords-api?hl=en