When first powering up your FBQ2496 it may be the case that all of the 20 available filter slots are assigned to PEQ (Parametric Equalizer).
This will prevent the LEARN function from working because there are no filter slots available to store troublesome frequencies as they are "learnt".
To check this, switch the unit on, the display will briefly show the firmware version and after a few seconds it will show RUN, this indicates that the unit is ready to be used and it will continue to display RUN until you enter another mode.
Next, press and hold the PEQ button until you see the letter P followed by a number. To remove any assigned PEQ filters turn the jog wheel anti clockwise until the display reads P 0 (note that the CHANNEL 1/L and CHANNEL2/R LED's will go out as you turn the rotary control). Once you have done this and removed all the PEQ filters, tap the PEQ button once to exit.
Now tap the LEARN button, the display will show S followed by a number. Turn the jog wheel clockwise to assign the filter slots to LEARN mode, you can use some or all of them depending on your application. Once you have done this simply tap the LEARN button once to exit.
Now when you initiate the AUTOLEARN sequence you will see the slots that you have assigned to LEARN illuminate as the troublesome frequencies are detected and stored.