I assume your radio is a small SDR such as a DVB-T USB dongle.
First back up a step – does your radio work with the short antenna that came with it connected to the radio, sitting on your desk?
This is an important test. It will tell you and us if the radio is working.
If your radio works with the short antenna sitting on your desk, but not with the antenna outside, there can be a number of reasons:
(1) there may be a problem with the feed line between the outside antenna and the radio
(2) there may be a problem with the outside antenna
(3) the outside antenna may be overloading your radio. This can be due to transmitters such as radio or television nearby.
Try your radio again with the short antenna that came with it and let us know what happens!