Ignition shielding can't be that difficult...can it?

Well, I intended to fly yesterday, but I also had some things to do to the airplane that have been bugging me. I wanted to try to shield the ignition so that my radio would receive and transmit a clearer signal. I started by installing round wire braid on the wires for one coil. I intended to do this for all four wires, but I didn't order enough braid. So here I am, in the calmest part of the day, wasting time installing this shielding braid, when I could have been flying instead. Oh well.

After about an hour and a half, I get the wires installed back on the plane and started it up. It ran good, so I put on my warm suit, grabbed my gloves and goggles, put on my headset and strapped my GPS to my leg. It sounds easy enough, but at 70 degrees in the hot sun, it gets really warm, really fast! So I'm all strapped in and I taxi a bit away from the hangar and rev up to 3500 RPM to check the dual ignition. I flip one switch and didn't hear any RPM drop. I flip the switch back on and flip the other off, and the engine quits! I unstrap and pull off all my flying gear and investigate. I couldn't find what was making the engine run on only one set of plugs. The only thing I changed was the shielding! I checked the coils individually by swapping places. Both coils would run when using the unshielded wires, while neither would run using the shielded wires! I couldn't believe it. Anyway, I took off the braid off the one set of wires and reinstalled everything, and it worked just fine. I'm at a loss....

Anyway, by this time the wind had kicked up to 15-20 knots and I didn't want to fly. I waited around until about 4:00 and the wind never did die down, so I went home.