Chartopen error

Hi,

I'm using an old mql4 editor (build 509) to compile and modify an existing indicator and

would like to use ChartOpen(). All I need to do is just compile so I can copy the ex4

to the new MT4 (build 840) and use ChartOpen like it was intended.

I added some code like this to just take the call in this format and link it run time.

extern int ChartOpen(string symbol, int period);

But when I compile it says:

ChartOpen: no dll defined for the imported function.

Is there any other way to get this to work ?