Web page address can use parameter?

Hi, I am a newbie and I have a question about parameterizing.
I created simple project that consists of fixed rate, web page runner, and statistics.
and I ran it via command line for using parameter, then I've gotten a error.

16:27:03,531 ERROR [WebRunner] Exception in closure sample:
java.lang.IllegalArgumentException
 at java.net.URI.create(Unknown Source)
 at org.apache.http.client.methods.HttpGet.<init>(HttpGet.java:69)
 at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
 at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
 at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
 at java.lang.reflect.Constructor.newInstance(Unknown Source)
 at org.codehaus.groovy.reflection.CachedConstructor.invoke(CachedConstructor.java:77)
 at org.codehaus.groovy.runtime.callsite.ConstructorSite$ConstructorSiteNoUnwrapNoCoerce.callConstructor(ConstructorSite.java:102)
 at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallConstructor(CallSiteArray.java:54)
 at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callConstructor(AbstractCallSite.java:182)
 at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callConstructor(AbstractCallSite.java:190)
 at GroovycomeviwareWebRunner$_run_closure13.doCall(GroovycomeviwareWebRunner:192)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
 at java.lang.reflect.Method.invoke(Unknown Source)
 at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
 at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:233)
 at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:272)
 at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:885)
 at groovy.lang.Closure.call(Closure.java:405)
 at com.eviware.loadui.groovy.GroovyScriptSupport.invokeClosure(GroovyScriptSupport.java:134)
 at com.eviware.loadui.groovy.categories.GroovyRunner.sample(GroovyRunner.java:47)
 at com.eviware.loadui.impl.component.categories.RunnerBase.doSample(RunnerBase.java:496)
 at com.eviware.loadui.impl.component.categories.RunnerBase.access$700(RunnerBase.java:70)
 at com.eviware.loadui.impl.component.categories.RunnerBase$Worker.run(RunnerBase.java:773)
 at com.eviware.loadui.util.dispatch.CustomThreadPoolExecutor$Worker.run(CustomThreadPoolExecutor.java:188)
 at java.lang.Thread.run(Unknown Source)
Caused by: java.net.URISyntaxException: Illegal character in authority at index 7: http://${=System.getProperty("myURL")}
 at java.net.URI$Parser.fail(Unknown Source)
 at java.net.URI$Parser.parseAuthority(Unknown Source)
 at java.net.URI$Parser.parseHierarchical(Unknown Source)
 at java.net.URI$Parser.parse(Unknown Source)
 at java.net.URI.<init>(Unknown Source)
 ... 28 more
16:27:03,533 ERROR [BaseCategory] Exception when calling 'sample'
java.lang.IllegalArgumentException
 at java.net.URI.create(Unknown Source)
 at org.apache.http.client.methods.HttpGet.<init>(HttpGet.java:69)
 at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
 at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
 at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
 at java.lang.reflect.Constructor.newInstance(Unknown Source)
 at org.codehaus.groovy.reflection.CachedConstructor.invoke(CachedConstructor.java:77)
 at org.codehaus.groovy.runtime.callsite.ConstructorSite$ConstructorSiteNoUnwrapNoCoerce.callConstructor(ConstructorSite.java:102)
 at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallConstructor(CallSiteArray.java:54)
 at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callConstructor(AbstractCallSite.java:182)
 at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callConstructor(AbstractCallSite.java:190)
 at GroovycomeviwareWebRunner$_run_closure13.doCall(GroovycomeviwareWebRunner:192)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
 at java.lang.reflect.Method.invoke(Unknown Source)
 at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
 at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:233)
 at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:272)
 at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:885)
 at groovy.lang.Closure.call(Closure.java:405)
 at com.eviware.loadui.groovy.GroovyScriptSupport.invokeClosure(GroovyScriptSupport.java:134)
 at com.eviware.loadui.groovy.categories.GroovyRunner.sample(GroovyRunner.java:47)
 at com.eviware.loadui.impl.component.categories.RunnerBase.doSample(RunnerBase.java:496)
 at com.eviware.loadui.impl.component.categories.RunnerBase.access$700(RunnerBase.java:70)
 at com.eviware.loadui.impl.component.categories.RunnerBase$Worker.run(RunnerBase.java:773)
 at com.eviware.loadui.util.dispatch.CustomThreadPoolExecutor$Worker.run(CustomThreadPoolExecutor.java:188)
 at java.lang.Thread.run(Unknown Source)
Caused by: java.net.URISyntaxException: Illegal character in authority at index 7: http://${=System.getProperty("myURL")}
 at java.net.URI$Parser.fail(Unknown Source)
 at java.net.URI$Parser.parseAuthority(Unknown Source)
 at java.net.URI$Parser.parseHierarchical(Unknown Source)
 at java.net.URI$Parser.parse(Unknown Source)
 at java.net.URI.<init>(Unknown Source)
 ... 28 more

Do you have any idea about it? or did I something wrong?

Thanks in advanced.
Jake