Much like a cellphone in a basement or a radio in a tunnel, your goTenna device's signal can be affected by physical obstacles. So look around! If you're in a ravine, behind a big boulder, or blocked by a large building, you're likely in a "radio shadow." Try elevating the device (or standing on a higher surface) or getting around the obstacle. Just because your messages stopped getting through at one point, doesn't mean they won't get through later at even greater distances if you find a friendlier spot from which to broadcast!
We strongly advise that you try to put it as high up on you as possible. We recommend hanging the device from a strap or clip on the upper side of a backpack. You can use goTenna on your belt loop or otherwise have it lower down, but you will experience a noticeable performance drop even over the short difference in altitude from your shoulder to your hip.
If you're trying to get more range by elevating the device, hold it by the nylon strap, as holding the device itself may drastically decrease goTenna's performance.