[xwiki-users] Problem with a Downloaded Macro (RSSAggregator)

I'm getting this after installing the RssAggregator macro XAR and using it in a page:

Failed to execute macro: groovy

org.xwiki.rendering.macro.MacroExecutionException: You don't have the right to execute this script at org.xwiki.rendering.macro.script.AbstractJSR223ScriptMacro.execute(AbstractJSR223ScriptMacro.java:134) at org.xwiki.rendering.macro.script.AbstractJSR223ScriptMacro.execute(AbstractJSR223ScriptMacro.java:50) at org.xwiki.rendering.internal.transformation.MacroTransformation.transformOnce(MacroTransformation.java:175) etc...

Ideas? Rick