Remote debug X11 from Mac to Ubuntu

Hi.

I'm trying to write a wxPython application that will run on my Linux box, but be coded and debugged on my Mac.

The code is identical; the SSH connection is identical to a non-GUI app I just wrote. The code runs fine locally on both machines, but not with a remote interpreter.

On my Mac, I get the following error message in the PyCharm terminal output:

ssh://XXX@10.0.0.53:22/usr/bin/python3.5 -u /home/XXX/PycharmProjects/joe/wxdemo.py
Unable to access the X Display, is $DISPLAY set properly?

Does anyone know how to resolve this? 

Thanks.