Amateur Radio - APRS (KJ4NET)?

We are attempting to track a high altitude balloon using APRS equipment. We have not been able to get adequate range on ground level (< 1.5 miles). After some extensive troubleshooting, we believe that our antenna is to blame. We built a dipole antenna for a specific frequency (144.39 MHz). We followed the directions for building a dipole antenna. We used a center insulator with two arms made of uninsulated copper wire. Our connections are well soldered and the lengths of the arms are correct. Surprisingly, we have better range with the cheap omni-directional antenna that came with a small handheld radio than with the dipole antenna. Without seeing a picture of the antenna, does anyone have any ideas on where we might be going wrong? Or even some good links to information regarding the construction and use of dipole antennas? By the way, my callsign is KJ4NET.