Android中运行一个项目时，模拟器报错?报错

运行一个项目时，模拟器报下面的错：

The application ...has stoped unexpectedly,please try again.

logcat中的错误信息是java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.neu/com.neu.Business.MainActivity}: java.lang.ClassNotFoundException: com.neu.Business.MainActivity in loader dalvik.system.PathClassLoader[/data/app/com.neu-1.apk]

我的MainActivity代码如下：

public class MainActivity extends TabActivity{

 private TabWidget mTabWidget;
 private TabHost mTabHost;

 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);

  mTabHost = getTabHost();

  //将要显示的Activity载入TabHost控件  
  setTabIndicator("已订购", 1, new Intent(this, Business_ordered_Activity.class)); 
  setTabIndicator("WIFI",2,new Intent(this,Wifi_Activity.class));
  setTabIndicator("未订购", 3, new Intent(this,UnOrdered_Activity.class));
  setTabIndicator("其他", 4, new Intent(this,Other_Activity.class));
 }
 private void setTabIndicator(String title,int nId,Intent intent){
  
  //指定Tab样式
  View view = LayoutInflater.from(this.mTabHost.getContext())
    .inflate(R.layout.tab_style, null);
  TextView text = (TextView)findViewById(R.id.tab_label);
  String strId = String.valueOf(nId);
  text.setText(title);
  
  //创建一个新的Tab
  TabHost.TabSpec localTabSpec = mTabHost.newTabSpec(strId)
    .setIndicator(view).setContent(intent);
  
  mTabHost.addTab(localTabSpec);
  
 }

}