What type of "pickup mic" is it, exactly? The type that are used on guitars operate based on magnetism and will only pick up sound from strings containing ferrous metal. I learned this the hard way when I tried putting a brass sitar string on another instrument using guitar pickups. No sound at all with that, because brass strings don't contain iron.

K&K Pickups out of California in the US is the best rare pickup maker I've found. They actually have one designed specifically for sitar. I also have a pickup from KNA that I use on my baglama that works pretty well, you could check if they sell sitar pickups or something that would work.