Good news I think I found the problem. A previously optional parameter has already become mandatory. I'm talking about:
BrokerBuy2 (char* Asset, int Amount, double StopDist, double Limit, double *pPrice, int *pFill): int pFill Optional output, the fill amount. Only used when the broker does not support FOK ordersand the order was only partially filled.
The documentation says that it is optional, but... I'll will fix the plugin to return it, so stay tuned for a new release soon.
I think I found the problem. A previously optional parameter has already become mandatory. I'm talking about: 
