Type of argument "string" in the dll

[second]

Hello!
Trying to work with NTDirect.dll from my C++ RAD2007 application and get exceptions often while trying to call SubscribeMarketData, UnsubscribeMarketData, MarketData.

What type of arguments should I use for "string", for

double

MarketData(string instrument, int type),
as example?

I tried to use: AnsiString, std::string, std::wstring and got exception.

Thanks in advance!

[NinjaTrader_Bertrand]

second, a regular string should do it - are you sure you get this exception because of the string type used?

Are you subscribing to MarketData first by calling SubscribeMarketData()?

http://www.ninjatrader-support.com/HelpGuideV6/Functions2.html

[second]

Are you subscribing to MarketData first by calling SubscribeMarketData()?

Yes, I did it first.
My sample code in Borland Builder C++:

 
AnsiString b = "ES 12-09";
NT = LoadLibrary("NTDirect.dll");
if (NT) {
    Connected2 = (Connected1 *)GetProcAddress(NT, "Connected");
    SubscribeMarketData2 = (SubscribeMarketData1 *)GetProcAddress(NT, "SubscribeMarketData");
    UnsubscribeMarketData2 = (UnsubscribeMarketData1 *)GetProcAddress(NT, "UnsubscribeMarketData");
    TearDown2 = (TearDown1 *)GetProcAddress(NT, "TearDown");
    MarketData2 = (MarketData1 *)GetProcAddress(NT, "MarketData");
    }
// Subscribe
if(SubscribeMarketData2)  SubscribeMarketData2(b);
Sleep(500);
 
// Get data
double s = MarketData2(b, 0);
Form1->Label1->Caption = s;
Sleep(500);

// Unsubscribe
if(UnsubscribeMarketData2) {UnsubscribeMarketData2(b); }
if(TearDown2) TearDown2();    
if (NT) FreeLibrary(NT);

And often I get exceptions, sometimes at SubscribeMarketData, sometimes at MarketData. I was adviced that it might be from using wrong type of argument.
What language the library was written? Delfi?

[NinjaTrader_Bertrand]

second, sorry not familiar with Borlands C++, but I believe you would need to convert the AnsiString being passed in - http://www.tek-tips.com/viewthread.c...=648627&page=9