Iphone 4 charger not working?

Everytime I go to plug in my Iphone 4 it has a yello triange and says charging is not supported with this accesory. I have bought 5 new chargers they worked for three months than went back to there same way. Any one no a souloution besides buying another charger.

Yeah sometimes when the charger gets damage it will say that is not supported. They have normal and extra long(10ft) chargers for sale here and there really good prices.http://www.howtoidevice.com/iphone