Error 4901 ERR_BOOKS_CANNOT_ADD when using MarketBookAdd

Debugging and Testing
#1

Code below fails with error 4901 (ERR_BOOKS_CANNOT_ADD)
regardless of broker. But I know such a code worked some time ago.
Possible reason(s)?

string symbol = "EURUSD";
int OnInit() {
        ResetLastError();
        if(SymbolSelect(symbol, true) != false) {
                if(!MarketBookAdd(symbol))
                        printf("market book add failed (%i)", GetLastError());
        }
        else printf("symbol select failed (%s)", symbol);
        return 0;
}
void OnBookEvent(const string& _symbol) {
        printf("DOM event for %s", _symbol);
}
void OnDeinit(const int reason) {
        MarketBookRelease(symbol);
}
#2

You have to choose a broker who provides Depth of Market for EURUSD.

#3

Thanks.

Sure, this is a prerequisite.

However, I can open the DOM manually on each of the brokers I have tested (i.e. FXCM, IronFX, NordFX, MQ demo server), yet the code keeps failing!?

#4

You can open the DOM but no one of the brokers you mentioned provide DOM data.

#5

I see.

Thanks…

#6

Could you advise any broker who provides DOM data?

#7

Noone can give a provider name which offer DOM datas?

Alternatively which is the keyword to search on google a provider name which offer DOM data

?