With a single indicator on the tree, the power bleeds across the indicator lamp to the opposite side and causes all lamps to flash. You actually need 3 diodes to correct the issue as well as running one side of the indicator lamp to ground. Kuryakyn makes a kit for doing this. The Valk shouldn't need it
You don't need 3 diodes, you only need 2, 1 goes to the orange and the other to the blue wire. The 2 diode kits cost less than 5 bucks at superbrightleds.