getting an exception on running sample of wso2cep - wso2

Question

I am a beginner in wso2cep. I want to execute the first sample of WSO2 CEP documentation. I use windows10 as operating system. I type the following command but i getting following exeption in Console output:
c:\wso2cep-4.0.0\samples\producers\http>ant Durl=http://localhost:9763/endpoints/httpReceiver -Dsn=0001
Buildfile: c:\wso2cep-4.0.0\samples\producers\http\build.xml
init:
compile:
[javac] c:\wso2cep-4.0.0\samples\producers\http\build.xml:71: warning: 'includeantruntime' was not set, defaulting to build.sysclasspath=last; set to
false
for repeatable builds
[copy] Copying 1 file to c:\wso2cep-4.0.0\samples\producers\http\temp\classes
run:
[echo] Configure -Durl=xxxx and ( -DfilePath=xxxx or -Dsn='sample number')
optionally use -Dusername=xxxx -Dpassword=xxxx
[java] [main] INFO org.wso2.carbon.sample.http.Http - Starting WSO2 Http
Client
[java] Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException:4
[java] at org.wso2.carbon.sample.http.Http.main(Unknown Source)
[java] Java Result: 1
BUILD SUCCESSFUL
Total time: 3 seconds
I add this line: <property name="filePath" value=""""/> to the build.xml file but I still get above exception. My build.xml file become as following:
<property name="carbon.home" value="${basedir}"/>
<property name="lib" value="${carbon.home}/repository/lib"/>
<property name="tempdir" value="${carbon.home}/tmp/setup"/>
<property name="output.dir" value="${carbon.home}/tmp/wso2"/>
<property name="filePath" value=""""/>
Should i change "filePath" to another thing? Should i add this line to build.xml file or change other lines? Please help and explain to me.