well ive been nymphing for quite a while but i have only been nymphing with success until i started treating the indicator like a dry fly in the sense that you really need it to be DRAG FREE! also play around with hook sizes and depths. a fish may refuse a size 16 but easily take an 18 of the same pattern. Also pay attention to the insects hatching and most of all as many of the guys before me said strike at any abnormal activity of your indicator. I hope you catch cause when you do it will become more clear to you . Good luck!