Anthis Nexus D2X Housing

I just bought a Anthis Nexus D2X housing, and am having a problem.  No instructions included but I've managed to figure everything out except one thing:  when I put the camera in the housing, I can't see anything through the eye piece.  It's completely focused out.  Is there some sort of diopter lens that is supposed to be used?  Obviously when I look through the viewer on the camera itself, everything is fine. It's just when I close up the housing, and look through eyepiece it's just a blur

yes, you need a diopter eye piece installed on your camera. it comes with the housing. you can ask fun-in for details cause they sell nexus housing.

https://www.fun-in.com.tw