Storm InvalidTopologyException: null

backtype.storm.generated.InvalidTopologyException: null
    at backtype.storm.daemon.common$validate_structure_BANG_.invoke(common.clj:151) ~[storm-core-0.9.0.1.jar:na]
    at backtype.storm.daemon.common$system_topology_BANG_.invoke(common.clj:287) ~[storm-core-0.9.0.1.jar:na]
    at backtype.storm.daemon.nimbus$fn__5528$exec_fn__1229__auto__$reify__5541.submitTopologyWithOpts(nimbus.clj:932) ~[storm-core-0.9.0.1.jar:na]
    at backtype.storm.daemon.nimbus$fn__5528$exec_fn__1229__auto__$reify__5541.submitTopology(nimbus.clj:950) ~[storm-core-0.9.0.1.jar:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.6.0_65]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) ~[na:1.6.0_65]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) ~[na:1.6.0_65]
    at java.lang.reflect.Method.invoke(Method.java:597) ~[na:1.6.0_65]
    at clojure.lang.Reflector.invokeMatchingMethod(Reflector.java:93) ~[clojure-1.4.0.jar:na]
    at clojure.lang.Reflector.invokeInstanceMethod(Reflector.java:28) ~[clojure-1.4.0.jar:na]
    at backtype.storm.testing$submit_local_topology.invoke(testing.clj:236) ~[storm-core-0.9.0.1.jar:na]
    at backtype.storm.LocalCluster$_submitTopology.invoke(LocalCluster.clj:19) ~[storm-core-0.9.0.1.jar:na]
    at backtype.storm.LocalCluster.submitTopology(Unknown Source) ~[storm-core-0.9.0.1.jar:na]
    at storm.starter.ApacheAccessLogTopology.main(ApacheAccessLogTopology.java:68) ~[classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.6.0_65]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) ~[na:1.6.0_65]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) ~[na:1.6.0_65]
    at java.lang.reflect.Method.invoke(Method.java:597) ~[na:1.6.0_65]
    at com.......