If you just got that radio look in to getting the firmware modified. If you need info on it pm me. you will be much happier with the hacked FW. but yea check your antenna, and also the RX that comes with the gt3bs have had issues on quality control where the antenna wasn't soldered properly, and they experienced the same thing you are seeing now.
If nothing else fixes it open it up and see that all the soldered parts are done right. You might be able to get it replaced by the vendor, but as far as a waaranty, they are from china, I'm not sure how that will work
a new rx is only $8 I do have an extra one, if you can't get yours to work we can see if you want to work something out, maybe we can split shipping or something.