I attached cells in collagen and to check cell viability , I stained with calcin-AM+PI to distinguish between live/dead cells. but, I am getting both the signals in for PI and Calcin-AM for the same cells. in addition to it i am getting background of collagen in GFP imaging. what does it suggests ,whether my cells are dead or alive? is there any method to seperate out live/dead cells after staining.