The n810's ambient light sensor is the main reason ASUI doesn't change the value, because ASUI would reset the brightness everytime ALS changed it
Was the rest of the applet working correctly (does it map ASUI when pressed)? Were other applets working or was the statusbar frozen? When BME code (new drain indicator) was having problems it would block hildon-desktop indefinitely and all applets on statusbar and desktop would freeze.
If the applet isn't frozen try opening asui-settings and toggle cpu overlay off and on to see if it does anything. Could be a race condition that caused the cpu refresh timer to be destroyed.
I will be leaving today and won't be able to work on ASUI for the rest of the year, unless I come back early. I have given maacruz access to the project so if anyone wants to write patches that add new features or fix problems then he can apply them.