Adding route entry fails with different gateways

I am using Windows IP helper functions to add an entry to the routing table which directs all requests to the 82.x.x.x through a VPN connection which has an interface IP 192.168.x.x. The VPN connection is started through a call to RasDial().

When I use my local network's router IP 10.0.0.1as the gateway, which is also the default gateway, the CreateIpForwardEntry() successfully adds the new route to the route table. But I want to make the gateway for that connection same as the 192.168.x.x, but when I try that, the CreateIpForwardEntry() fails with error ERROR_INVALID_PARAMETER.

I tried with different metrics for the connection, but none of them work. Here's the code segment I am using.

MIB_IPFORWARDROW  routeEntry;      //      route entry data
      memset(&routeEntry, 0, sizeof(MIB_IPFORWARDROW));
      routeEntry.dwForwardDest=inet_addr("82.x.x.x");
      routeEntry.dwForwardMask=inet_addr("255.255.255.255");
      routeEntry.dwForwardAge=0;

     

      CString s;
      DWORD dwIndex=0,dwMask=0, dwVPNIP;;
      in_addr in;
      dwVPNIP=GetVPNIP(&dwIndex);
      in.s_addr=dwVPNIP;
      routeEntry.dwForwardNextHop=dwVPNIP;//inet_addr("10.0.0.1");
     
      routeEntry.dwForwardIfIndex = dwIndex;
     
   
    routeEntry.dwForwardMetric1 = 20;      //      hard coded ************

    // some default values
    routeEntry.dwForwardProto =MIB_IPPROTO_LOCAL;// MIB_IPPROTO_LOCAL;
    routeEntry.dwForwardMetric2 = 1;
    routeEntry.dwForwardMetric3 = 1;
    routeEntry.dwForwardMetric4 = 1;
      DWORD dwStatus;

      if ((dwStatus=CreateIpForwardEntry(&routeEntry))!= NO_ERROR)
    {
            if(dwStatus==ERROR_INVALID_PARAMETER)
                  MessageBox("Invalid param");
            s.Format("Adding entry failed Status %d",dwStatus);
        MessageBox(s);
    }

What might have cause this problem?

Thanks.
Shaf81