Patellar taping is a fairly new treatment option for patellofemoral pain syndrome (pain behind the kneecap). The tape helps the kneecap to stay in its proper place as it moves up and down with knee motion. It also helps unload the force or pressure on the kneecap that contributes to pain. Many people find that, with the tape in place, they can do most activities without pain.
Recent research has shown that continued pain after taping may mean the taping was not done properly. Pay close attention to the specific taping done on those days when the tape reduces pain. Compare this to the taping method used on days when the pain continues despite taping.
If this doesn't help, contact the physical therapist or physician who showed you the taping method. Very likely, the cause of the problem can be quickly and easily identified and corrected.