I'm calculating pagerank with the help of centibin, while uploading the network (in .xml) i got the following error.

java.lang.NullPointerException
    at centibin.dd.b(Unknown Source)
    at centibin.dd.a(Unknown Source)
    at centibin.F.h(Unknown Source)
    at centibin.dX.a(Unknown Source)
    at centibin.bU.a(Unknown Source)
    at centibin.du.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)

How to solve this error? Thanks