If indeed you are trying to make the RapidWeaver Contact Form send to a Gmail address, I don’t think that is going to work anymore.
By now, all the problems with spam and DDoS attacks means that a lot of hosting companies have changed their policies. Most now only allow contact forms to send messages to email addresses they themselves are hosting. That way if something goes wrong, the problem is contained.
Because all the contact form processing happens server-side, it might be better to open the server error logs and see if anything noteworthy is being logged there. The hosting company can help you with this, if you speak to them.
There are alternative RapidWeaver addons around which can handle form correspondence differently, if you absolutely do need a system that can send messages to a Gmail address. TouchBase and Formulate stacks, to name a few.