Problème avec Eclipse

package com.fr;    

import android.app.Activity;    
import android.os.Bundle;    
import android.widget.Button;    

public class projet extends Activity {    
    Button bouton1;    
 Button bouton2;    
     
    public void onCreate(Bundle savedInstanceState) {    
        super.onCreate(savedInstanceState);    
        setContentView(R.layout.main);    
     
        bouton1= (Button) findViewById(R.id.bouton1);    
        bouton2 = (Button) findViewById(R.id.bouton2);    
    }    
}

<?xml version="1.0" encoding="utf-8"?>    
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    
    android:orientation="vertical"    
    android:layout_width="fill_parent"    
    android:layout_height="fill_parent"    
    >    
<TextView      
    android:layout_width="fill_parent"     
    android:layout_height="wrap_content"     
    android:text="@string/hello"    
    />    
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    
     android:orientation="horizontal"    
     android:layout_width="fill_parent"    
     android:layout_height="wrap_content"    
     android:padding="10px">    
         

<Button    
 android:id="@+id/bouton1"    
 android:layout_width="wrap_content"    
 android:layout_height="wrap_content"    
 android:text="boutton1" />    
     
 <Button    
 android:id="@+id/bouton2"    
 android:layout_width="wrap_content"    
 android:layout_height="wrap_content"    
 android:text="boutton2" />    
     
</LinearLayout>    
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>    
<manifest xmlns:android="http://schemas.android.com/apk/res/android"    
      package="com.fr"    
      android:versionCode="1"    
      android:versionName="1.0">    
    <application android:icon="@drawable/icon" android:label="@string/app_name">    
        <activity android:name=".projet"    
                  android:label="@string/app_name">    
            <intent-filter>    
                <action android:name="android.intent.action.MAIN" />    
                <category android:name="android.intent.category.LAUNCHER" />    
            </intent-filter>    
        </activity>    

    </application>    
    <uses-sdk android:minSdkVersion="4" />    

</manifest> 

Re-installation failed due to different application signatures.    
You must perform a full uninstall of the application. WARNING: This will remove the application data    
Please execute 'adb uninstall com.fr' in a shell.    
Launch canceled!