I had the same problem but have now got the knack !!
I find that its best to hold the lamb on its back on your thighs while kneeling.... open the band and put over the purse, pull the purse through........then run ur other hand down help the little nuts into the purse...at the same time closing the band, so when they are both in close it and pop off the band from the applicator, it took me 3 or 4 before I got the hang of it
hop that helps