Can not install nor delete Poweramp - Error code "-24"

[pimpl]

I recently bought a Samsung Galaxy S4 Black-Edition (Modelnumber: GT-I9505)

 

.. Since the update from the firmware-version I9505XXUGNF1 everything has been working perfectly for three weeks, but yesterday when I restarted my phone suddendly the error massage "System UIDs Inconsistent... [...] need to wipe [...]" appeared before I was asked to type in my PIN. I Ignored the message and started my phone as usual, but suddenly my nova prime launcher lost some of its homescreen shortcuts and all of the widgets. Note that this "System UIDs Inconsistent"-Message disappeared after I restarted the device.
.. After manually restoring the shortcuts and widgets on my homescreens I noticed that power amp was missing. Ever since I was trying to reinstall it from the google Playstore I get the error message "Unknown Error code during application install: "-24" ", so I'm not able to get that app again (I got the premium version - can't download/install the unlocking-key file either).

I got the premium version of titanium Backup installed and did a complete backup of all user and systemapps (app + data) a month ago , but I can not restore power-amp via Titaniumbackup, as is stucks after selecting to restore Poweramp (progress-bar always stays at 0%).

I searched for all 'com.maxmpz'-files on my device and deleted them, but the error persists no matter what I tried (delet download helper/ google playstore data..)

I found one reference to my problem telling the pro key from the playstore and the homepage are not the same.. that information definitly does not solve my problem!

So, if anyone knows how to fix that problem I'm VERY thankful for any sort of help!

 

Note that I am NOT willing to factory restore ma phone!

[yuuki]

System UIDs Inconsistent.

CWM/TWRP - advanced - fix rights could help with that.

[Magadaner]

Can you please write your issue details to poweramp.maxmpz@gmail.com?

 

Thanks!