I created a friction raster from a street center line and I am using the cost distance tool to measure walkability. I have redone the analysis several times and 9 out of the 50 points create zero values every time. I am running the cost distance tool one point at a time. When I run the tool on all 50 points at once there is not a problem. When I zoom up on the points I see that they are on the raster, so I am not sure what is happening. Has anyone had this problem?