Can't get long from dll's struct with JNA!!!

Question

Hi,
I have trade.dll witch contains structs and just informational fields. For example like this:
long getInstrumentCount ();
struct Instrument {
long id;
char MarketName[15];
char SectorName[15];
char GroupName[15];
char ShortName[15];
char Name[100];
double Open;
struct Instrumnet getInstrumentByNum(long)
Here is Java mapping:
public interface TradeDll extends StdCallLibrary {
public static class Instrument extends Structure
public static class ByValue extends Instrument implements Structure.ByValue { }
public Pointer id;
public byte[] marketName =new byte[15];;
public byte[] sectorName=new byte[15];
public byte[] groupName=new byte[15];
public byte[] shortName=new byte[15];
public byte[] name=new byte[100];
public double open;
long getInstrumentCount();
Instrument.ByValue getInstrumentByNum(long n);
So, getInstrumentCount and getInstrumentByNum work fine, but I can't get id value from returned stuct by getInstrumentByNum(long n).
First I've tried to declare id like just long but, it takes 8 byte and took 4 byte from next field. (I think in dll file for id field allocates only 4 bytes).
Second I've tried to declare id like NativeLong, but it returns "java.lang.IllegalArgumentException: Unsupported structure field type class com.sun.jna.NativeLong" exception.
Third I've tried to declare id like Pointer, but I couldn't get long value from Pointer. When I've tried get long with pointer.getLong(0) and pointer.getNativeLong(0) JVM prints "An unexpected error has been detected by Java Runtime Environment:
Fourth I've declared like this byte[] id = new byte[4], but long type in Java needs 8 bytes.
I'm sitting on this problem already 2 weeks!
Can anybody help me, please!
Thanks!

Answer 1

Here is my virtual instrument>>>>
Attachments:
SOLO_esib_problem_noreading.vi.vi ‏29 KB
Immagine.GIF ‏66 KB