How to connect Steinberg MR816 to an external Effect unit


I need to comment my MR to my effect processer to be used stand-alone without a computer. It has a mono input and two outputs left and right.

I connect INSERT I/O jack 1 to Input of effect ( the tip that says send) and connect the tip that says 'return" to the output of the effect unit. However, when I do this, I hear absolutely nothing! unless I remove the cable out of MR Insert I/O jack.

Any help would be appreciated.