That means the procedure was not done correctly.
Go to Control Station, pull the left menu, select “Detect Maximum Brightness”
A dialog pops up, do not press any button
Pull the top Android Menu and set brightness to the maximum
Now pull the top Android Menu back up to see DMD2
In DMD2 now press SAVE in the dialog that should still be visible
That is it.
By the way, we are removing brightness settings in DMD2 for the next big update.