You might want to see if you haven't inadvertently grounded the mag with the p-lead (some stray part of the p-lead is grounding to the case). It's a little tricky to find, but I've had this happen.
(You shouldn't try starting with the p-lead disconnected, the engine might kick back and cause some damage. You want the right mag off line when you try to start.)
RV7A (N7101) - Flying 10/2008