the tomos has a two coil system because (or so tomos said) for safety reasons.
as you already figured out if you hit the brake the flow of electricity ends at the burnt out bulb and the moped dies.
1 make sure the wire is grounded and placed in the wiring strip properly
2 if that doesn't work buy a bulb at a mejier or an auto shop that is made to handle 12 volts. It won't be as brite but it won't burn out.
write back and tell me if it works