i made a website for a client and put google adsense on it but it keeps showing public service ads instead of paying ones. i even checked with keywords (for the content), relevant content , did the right seo work , and even uploaded robot.txt file to the public html folder. i can see the ads (the paid ones) but my client says he can see public service ads or a mix of both PSAs and paid ones. what is wrong and how to fix this ?