the way i was told to do it was to tie it on with a small loop, then put a pair of needle nose pliers into the loop a small ways then pull the handles out so the pliers are pushing on the string and loop titen like hell. then cut off the tag ends and melt them into a big mushroom like NCYankeesaid but dont heat to long or it will make it weak then titen it again and the ends should stay put. it sounds like u just didnt titen it first or u cut the tag ends to short but the good thing is string is cheap so u can practise a few times withoutitspending to much money. andif u pull hard enof on the pliers it will show u if it will work or not because thay put more force on the loop than pulling back the bow will