FXCodeBase.COM: Forex Chart Indicators and Development

I get this error. Here is the error and function below. Causes the strategy to stop, was working good last time I used this.

C:/Program Files (x86)/Candleworks/FXTS2/Strategies/Custom/XXXXXXXX.lua:449: bad argument #2 to '?' (no value) 12/13/2016 13:36:44

function ExtTrace(message)
local theDate = core.dateToTable(core.host:execute("convertTime", 1, 4, math.max(instance.bid:date(instance.bid:size() - 1), instance.ask:date(instance.ask:size() - 1))));
Line 449--core.host:trace(string.format("%d/%02d/%02d %02d:%02d:%02d ", theDate.year, theDate.month, theDate.day, theDate.hour, theDate.min, theDate.sec) .. " " .. message);
end

Can you provide strategy code?

Thank you Apprentice for replying.

I should have re-posted that I located the problem in the code.