To read about legal issues, please go to the legal section on this forum.
There is no law against any type of advertising in general – it is a right guaranteed to US citizens as freedom of speech.
There has been no specific law passed that adresses advertising online gambling.
There a bunch of people who wish there was and just pretend there is in order to scare people.
As to why your site is not producing – I have no idea. You need to show and tell a lot more.