Yes, Istock is really slow in getting the images approved, I only got 8 approved, still has 21 on the que, of course I only started exploring microstock since July 8th, joined DT,FT, Istock,( was rejected the initial 3, then got accepted the next 8 out of 9 ), but rejected by SS(50%) and BST(100% rejection).
So far with 55 images at FT, 4 sales, 15 more pending
21 images with DT no sales 30 more pending
35 pending with BST, nothing approved yet
8 online with IS, 21 pending
Sure it takes a lot of patience to build up your portfolio.