I am trying get APC statistics

I am trying get APC statistics by print_r(apc_cache_info('user'));

It work fine. However, when I try to
print_r(apc_cache_info('user', true));

My browser gives me a white screen.

I have tried

<?php
ini_set('display_startup_errors',1);
ini_set('display_errors',1);
error_reporting(-1);
print_r(apc_cache_info('user', true));

still white screen...

Any clue to resolve it?

Thanks.

P.S.: it happens again when installing New Relic APC plugin.