I followed the example simulation 5.2 directional RNA-seq Protocol paramater file and usage ,the error that java nullpointerexception occurred.the java version is 1.8.2,and the environment variable is correct.

the command line code is  flux-simulator -t simulator -p hg19_stranded.par

error :

Processing Fragments ********** OK (00:00:45)
51435495 mol: in 4999450, new 46436045, out 51435495
avg Len 316.02563, maxLen 1036
preparing transcript sequences *java.lang.NullPointerException
at barna.model.Graph.getRAF(Graph.java:1101)
at barna.model.Graph.readSequence(Graph.java:522)
at barna.model.Graph.readSequence(Graph.java:479)
at barna.model.Graph.readSequence(Graph.java:430)
at barna.model.Transcript.getSplicedSequence(Transcript.java:451)
at barna.flux.simulator.fragmentation.Fragmenter.getMapTxSeq(Fragmenter.java:376)
at barna.flux.simulator.fragmentation.Fragmenter.process(Fragmenter.java:498)
at barna.flux.simulator.fragmentation.Fragmenter.call(Fragmenter.java:217)
at barna.flux.simulator.SimulationPipeline.call(SimulationPipeline.java:428)
at barna.flux.simulator.SimulationPipeline.call(SimulationPipeline.java:53)
at barna.commons.launcher.Flux.main(Flux.java:196)
java.lang.NullPointerException

I want to know why happened this?