OPC COM connection between 64 and 32 bit systems

The point is that I can connect to deltaV servers only after installing DeltaV OPC Remote on Ignition side.
It is ok using 32 bit ignition, but if I set java memory heap size more than 1.5 Gb, gateway doesn’t start or hangs just after start. I can enlarge ammout of memory for 64 bit java and ignition but then i loose connection with Deltav sources.
One of two problems is to be settled.