No signal from Ditto Looper in the FX Loop of the Avid Eleven Rack

[dcasner64]

I am able to use the ditto looper by plugging my guitar into the input and headphones into the output of the ditto looper. I can record a loop, hear it in the headphones, and then play along with it. However, when I connect a 1/4 cable from the Eleven Rack FX Loop Send into the input of the Ditto Looper, then connect another 1/4 cable from the Eleven Rack FX Loop Return to the output of the Ditto Looper, I cannot hear any output from the ditto looper via the headphones connected to the Eleven Rack headphone jack. I have checked the signal path of my Eleven Rig and the FX Loop is not bypassed. How would you go about using the Ditto Looper with the Eleven Rack? Is anyone else having this problem?