Adding unequal arrays of different symbols

I am trying to add daily volumes of some symbols to plot them but those symbols arrays doesn't have the same size so it plots only the size of the smallest on, i need it to add zero if this day isn't available instead of stopping

Here is my code

symlist = CategoryGetSymbols( categoryMarket,2);
//Loop Over market stocks
vol = 0;
TotalTurnOver = 0;

for ( i = 0; ( sym = StrExtract( symlist, i ) ) != ""; i++ ) 
	fc = Foreign( sym, "V" );
	vol = vol+fc;
Plot(vol,"Volume",colorRed ,style = styleHistogram );

You may import an index such as SP500 having all historical data to create a composite (using StaticVarAdd or AddToComposite).

Can you please explain more?, i tried using StaticVarAdd but it isn't available.

You don't need to do anything special. Foreign automatically pads data to current symbol see documentation (please read COMMENT part).

The only thing you may need is to convert Null to zero, as missing bars may be Null:

// loop body
fc = Foreign( sym, "V" );
vol += Nz( fc ); // Null to zero function

Please note however that placing such code in a chart is not really good performance wise. It is better to create composite as @codejunkie explained (see also

StaticVarAdd mentioned earlier is available only for registered users (v6.28).

Thank you Tomasz it finally worked !
i will check the composite also.