I have 20 pairs of origin and destination. And, also I have 20 different line barriers for those pairs, as I want to determine the shortest path between them. If the name of the origin and destination is 100 then the name of the corresponding barrier is also 100. So, I build the model based upon the algorithm in previous study. The model have a iterator that will select the pair of O-D and corresponding barrier one at a time, to find the shortest path between Origin and Destination. The problem is: although there is a route between them, final output doesn't have shortest path for some of the O-D pairs. When I try to do it one by one using the same model, it works (i.e. shortest path for all of them is obtained easily). But, when I try to do it using whole data at once, only 6 out of 20 shortest path is obtained. The error I get is " No route from location 1 to location 2". I have tried every possible way to solve this, at least I think so. Is there any solution to solve this ? | 
