Error #16 means Poweramp received non-Google signature during the license check. This is known behavior of cracked/modded Play app - Poweramp won't be able to check license as license information is invalid.
Cracked Play always returns wrong signature for any Play response (even if app is actually legally purchased).
Please disable LVL emulation, Google Billing Emulation (or other similar switches) in LuckyPatcher or similar apps (or un-patch Play / core.jar - if modified Play is used and depending on LuckyPatcher version) for at least a day (24 hours) - so Poweramp is able to check itself (License Verified appears in settings).
