lambdaj ProxyUtil.createEnhancer exception

Question

Imported lambdaj successfully in my android app, however any filter, select or group operation raises this:

04-05 16:46:42.555: E/AndroidRuntime(8482): java.lang.ExceptionInInitializerError 
04-05 16:46:42.555: E/AndroidRuntime(8482): at ch.lambdaj.proxy.ProxyUtil.createEnhancer(ProxyUtil.java:89) 
04-05 16:46:42.555: E/AndroidRuntime(8482): at ch.lambdaj.proxy.ProxyUtil.createProxy(ProxyUtil.java:49) 
04-05 16:46:42.555: E/AndroidRuntime(8482): at ch.lambdaj.function.argument.ArgumentsFactory.createPlaceholder(ArgumentsFactory‌​.java:68)

a simple operation is for example: Group<Person> groupedPersons= group(people,by(on(Person.class).getAge()));