When connecting an FS-6 to a supported Roland or BOSS product, you must use a cable with TRS (stereo) connectors on each end. You can identify this type of connector by its two black rings.

Note: Don't use a standard guitar or instrument cable. These cables only have TS (mono) connectors on each end.

Alternatively, you can use a "stereo insert" cable. This is a specific type of "Y," or "splitter," cable that has a TRS (stereo) connector on one end of a cable that splits into two TS (mono) connectors.