There are two possible causes.

1. Is the [BEAT EFFECTS] – [ON/OFF] button set to [ON]? Press the [BEAT EFFECTS] – [ON/OFF] button and set [SND/RTN] to [ON].

2. Is the external effector properly connected to the [SEND] and [RETURN] terminals? Connect the external effector to the [SEND] and [RETURN] terminals. For details, see "Connecting the Input Terminals" in the operating instructions.