I am working on a network design problem (min-cost flow) to find the shortest paths for every set of start and destination nodes. Based on the set of inputs (arcs--(which are of the form (start,end) ) and cost) the program calculates the minimum cost from the start to destination (which is again specified as input parameters).

The program computes the correct set of costs in some instances by picking up the right values.
if the following are specified in the input --
start= 1
1 11 0.3063
1 2 0.2205
2 11 0.1110

The program prints out cost from 1 to 11 as 0.3315 instead of 0.3063
However it computes the correct results in some cases. Please let me know of some ideas of where the problem could be.

Thanks in advance!