Yesterday I bought a new domain which I think is more proper with my ad. I forwarded the domain to the same hosting account as my former domain. And in order to avoid duplicate site problem, I redirected the new domain to the old one. Then I displayed the new domain in my adwords ads, but my ads were rejected by google for the inaccurate display url. Why could this happen? What should I do to solve the problem?
The domain name that people see in the ad must match what they see in the address bar when they land there. If they land on olddomain.com, then olddomain.com must be the display url.
As per Google guidelines, display URLs must be matched with the landing pages URLs, in your case display url is your new domain and landing page is old domain. This is the reason your ad has been rejected.