Is the [1, 2, 3, 4, MIC, CF.A, CF.B, MASTER] selector switch properly set? Turn the [1, 2, 3, 4, MIC, CF.A, CF.B, MASTER] selector switch and set it to the channel to which you want to apply the effect.

Is all the FX FREQUENCY HI/MID/LOW turned off? Press the FX FREQUENCY HI/MID/LOW button and select frequency range you wish to apply effect.