This error is an issue with the .sfz file of the Adodo patch. To correct this problem, download the attached file and copy it to the Garritan World Instruments > Instruments > Percussion > Africa folder.
On Windows, this folder is usually located in the Program Files > Garritan folder.
On Mac, this folder is usually located in the Applications > Garritan folder.
Replace this file with the one that exists in this folder. Relaunch the ARIA player and you should no longer get this error.