You got me on the right path Ajax.
I did some more googling about triggers and jacks and read from another stereo board that stereo 3.5mm jacks do not work the trigger, but mono do.
Is this true for the EP500/600 line?

mycableshop.com carries - 6 Foot Mono Patch Cable - 3.5mm Male to 3.5mm Male for $5 US, they also have a canadian side


I found this on another site.....connections 101 FYI

Plug or Jack--which do you need?
A "JACK" is a female "SOCKET" that mounts to a panel or onto a circuit board. A female receptacle that attaches to a cord is called an "INLINE JACK".
A "PLUG" is a male connector that attaches to a cord.
A PLUG that mounts on a panel is called a "CHASSIS MOUNT PLUG"
Male or Female connector--which GENDER is it?
A "FEMALE" connector has a "center hole"
A "MALE" plug has a "pin" for the center "tip" connection which fits into the Female "Jack"