Why does my two zone gas Weil Mclain H5 boiler turn off when the second zone calls for heat?

I have a gas fired hot water baseboard system, 2 zones with honeywell zone valves. Each zone works fine by itself. But if the 2nd zone calls for heat while the boiler is running for the 1st zone, it opens the 2nd zone valve ok but the boiler kicks off immediately. I think I have a wiring problem but I have no idea specifically what it is. I did recently attach some wires back after some had come loose when work was done there but I probably didn't get everything right - but it must be pretty close since everything else seems to work ok - the firing, valves opening/closing, thermostat triggering on/off. Any istance would be greatly appreciated.