JNI C++ DLL - 'UnsatisfiedLinkError: %1 不是有效的 Win32 应用程序'

I am trying to actually get JNI working before I dive in with my actual code, but after I compile a DLL from C++ and run my Java application I get:

Exception in thread "main" java.lang.UnsatisfiedLinkError: <snip>workspaceJNI test
ativejnitest.dll: %1 is not a valid Win32 application
    at java.lang.ClassLoader$NativeLibrary.load(Native Method)
    at java.lang.ClassLoader.loadLibrary1(Unknown Source)
    at java.lang.ClassLoader.loadLibrary0(Unknown Source)
    at java.lang.ClassLoader.loadLibrary(Unknown Source)
    at java.lang.Runtime.loadLibrary0(Unknown Source)
    at java.lang.System.loadLibrary(Unknown Source)
    at net.condorcraft110.jnitest.JNITest.main(JNITest.java:11)

用 Google 搜索了一下，我知道这通常是由于尝试使用 32 位 JVM 加载 64 位 DLL 引起的.但是，我的 JVM 是 64 位的，正如 sun.arch.data.model 等于 64 所证明的那样.

CLASSPATH = ../bin

vpath %.class $(CLASSPATH)

all : jnitest.dll

jnitest.dll : jnitest.o
    g++ -m64 -Wl,--add-stdcall-alias -shared -o $@ $<

jnitest.o : jnitest.cpp jnitest.h
    g++ -m64 -I"C:Program FilesJavajdk1.7.0_51include" -I"C:Program FilesJavajdk1.7.0_51includewin32" -c $< -o $@

jnitest.h : net/condorcraft110/jnitest/JNITest.class
    javah -verbose -classpath $(CLASSPATH) -o jnitest.h net.condorcraft110.jnitest.JNITest

clean :
    rm jnitest.h jnitest.o jnitest.dll

package net.condorcraft110.jnitest;

public class JNITest
{
    private static native void test();

    public static void main(String[] args)
    {
        System.out.println("sun.arch.data.model = " + System.getProperty("sun.arch.data.model"));

        System.loadLibrary("jnitest");

        test();
    }
}

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class net_condorcraft110_jnitest_JNITest */

#ifndef _Included_net_condorcraft110_jnitest_JNITest
#define _Included_net_condorcraft110_jnitest_JNITest
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class:     net_condorcraft110_jnitest_JNITest
 * Method:    loadPlugins
 * Signature: ()V
 */
JNIEXPORT void JNICALL Java_net_condorcraft110_jnitest_JNITest_test
  (JNIEnv *, jclass);

#ifdef __cplusplus
}
#endif
#endif

using namespace std;

#include <jni.h>
#include <iostream>
#include "jnitest.h"

extern "C" JNIEXPORT void JNICALL Java_net_condorcraft110_jnitest_JNITest_test(JNIEnv *env, jclass clazz)
{
    cout << "jni test successful" << endl;
}