Choice expression Mule Error

ERROR 2013-03-14 15:30:32,250 [defaultHttpConnector.receiver.02] org.mule.exception.DefaultSystemExceptionStrategy: Caught exception in Exception Strategy: null
java.lang.NullPointerException
    at org.mule.routing.filters.ExpressionFilter.getFullExpression(ExpressionFilter.java:140)
    at org.mule.routing.filters.ExpressionFilter.accept(ExpressionFilter.java:104)
    at org.mule.routing.ChoiceRouter.selectProcessors(ChoiceRouter.java:35)
    at org.mule.routing.AbstractSelectiveRouter.process(AbstractSelectiveRouter.java:194)
    at org.mule.processor.chain.DefaultMessageProcessorChain.doProcess(DefaultMessageProcessorChain.java:99)
    at org.mule.processor.chain.AbstractMessageProcessorChain.process(AbstractMessageProcessorChain.java:66)
    at org.mule.processor.AbstractInterceptingMessageProcessorBase.processNext(AbstractInterceptingMessageProcessorBase.java:105)
    at com.<path to my app>.mule.util.PerformanceLogInterceptor.process(PerformanceLogInterceptor.java:69)
    at org.mule.processor.AbstractInterceptingMessageProcessorBase.processNext(AbstractInterceptingMessageProcessorBase.java:105)
    at com.<path to my app>.mule.util.ServiceMetadataProcessor.process(ServiceMetadataProcessor.java:39)
    at org.mule.processor.chain.DefaultMessageProcessorChain.doProcess(DefaultMessageProcessorChain.java:99)
    at org.mule.processor.chain.AbstractMessageProcessorChain.process(AbstractMessageProcessorChain.java:66)
    at org.mule.processor.AbstractInterceptingMessageProcessorBase.processNext(AbstractInterceptingMessageProcessorBase.java:105)
    at com.<path to my app>.mule.monitoring.NewRelicMonitoringInterceptor.process(NewRelicMonitoringInterceptor.java:73)
    at org.mule.processor.AbstractInterceptingMessageProcessorBase.processNext(AbstractInterceptingMessageProcessorBase.java:105)
    at org.mule.processor.AsyncInterceptingMessageProcessor.process(AsyncInterceptingMessageProcessor.java:90)
    at org.mule.processor.chain.DefaultMessageProcessorChain.doProcess(DefaultMessageProcessorChain.java:99)
    at org.mule.processor.chain.AbstractMessageProcessorChain.process(AbstractMessageProcessorChain.java:66)
    at org.mule.processor.AbstractInterceptingMessageProcessorBase.processNext(AbstractInterceptingMessageProcessorBase.java:105)
    at org.mule.interceptor.AbstractEnvelopeInterceptor.process(AbstractEnvelopeInterceptor.java:55)
    at org.mule.processor.AbstractInterceptingMessageProcessorBase.processNext(AbstractInterceptingMessageProcessorBase.java:105)
    at org.mule.processor.AbstractFilteringMessageProcessor.process(AbstractFilteringMessageProcessor.java:44)
    at org.mule.processor.chain.DefaultMessageProcessorChain.doProcess(DefaultMessageProcessorChain.java:99)
    at org.mule.processor.chain.AbstractMessageProcessorChain.process(AbstractMessageProcessorChain.java:66)
    at org.mule.processor.chain.InterceptingChainLifecycleWrapper.doProcess(InterceptingChainLifecycleWrapper.java:56)
    at org.mule.processor.chain.AbstractMessageProcessorChain.process(AbstractMessageProcessorChain.java:66)
    at org.mule.processor.chain.InterceptingChainLifecycleWrapper.process(InterceptingChainLifecycleWrapper.java:87)
    at org.mule.construct.AbstractPipeline$1.process(AbstractPipeline.java:138)
    at org.mule.processor.chain.DefaultMessageProcessorChain.doProcess(DefaultMessageProcessorChain.java:99)
    at org.mule.processor.chain.AbstractMessageProcessorChain.process(AbstractMessageProcessorChain.java:66)
    at org.mule.processor.chain.InterceptingChainLifecycleWrapper.doProcess(InterceptingChainLifecycleWrapper.java:56)
    at org.mule.processor.chain.AbstractMessageProcessorChain.process(AbstractMessageProcessorChain.java:66)
    at org.mule.processor.chain.InterceptingChainLifecycleWrapper.process(InterceptingChainLifecycleWrapper.java:87)
    at org.mule.processor.chain.DefaultMessageProcessorChain.doProcess(DefaultMessageProcessorChain.java:99)
    at org.mule.processor.chain.AbstractMessageProcessorChain.process(AbstractMessageProcessorChain.java:66)
    at org.mule.processor.chain.InterceptingChainLifecycleWrapper.doProcess(InterceptingChainLifecycleWrapper.java:56)
    at org.mule.processor.chain.AbstractMessageProcessorChain.process(AbstractMessageProcessorChain.java:66)
    at org.mule.processor.chain.InterceptingChainLifecycleWrapper.process(InterceptingChainLifecycleWrapper.java:87)
    at org.mule.transport.AbstractMessageReceiver.routeMessage(AbstractMessageReceiver.java:195)
    at org.mule.transport.AbstractMessageReceiver.routeMessage(AbstractMessageReceiver.java:163)
    at org.mule.transport.AbstractMessageReceiver.routeMessage(AbstractMessageReceiver.java:150)
    at org.mule.transport.http.HttpMessageReceiver$HttpWorker.doRequest(HttpMessageReceiver.java:299)
    at org.mule.transport.http.HttpMessageReceiver$HttpWorker.processRequest(HttpMessageReceiver.java:258)
    at org.mule.transport.http.HttpMessageReceiver$HttpWorker.run(HttpMessageReceiver.java:163)
    at org.mule.work.WorkerContext.run(WorkerContext.java:310)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
    at java.lang.Thread.run(Thread.java:680)
ERROR 2013-03-14 15:30:32,261 [defaultHttpConnector.receiver.02] org.mule.exception.DefaultSystemExceptionStrategy: Caught exception in Exception Strategy: null
java.lang.NullPointerException
    at org.mule.transport.http.HttpResponse.setBody(HttpResponse.java:310)
    at org.mule.transport.http.HttpMessageReceiver$HttpWorker.buildFailureResponse(HttpMessageReceiver.java:435)
    at org.mule.transport.http.HttpMessageReceiver$HttpWorker.run(HttpMessageReceiver.java:208)
    at org.mule.work.WorkerContext.run(WorkerContext.java:310)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
    at java.lang.Thread.run(Thread.java:680)