title: crash when add and remove sprite in cocos2d
body: <p>i am doing something wrong, maybe someone could help me .</p>
  
  <p>when app is start i add a sprite as a child,from DB like this :</p>
  
  <pre><code>b_pic=[CCSprite spriteWithFile:basic_pic];
      b_pic.position=ccp(160,175);
      [self addChild:b_pic];
  </code></pre>
  
  <p>then i do things,and run animation, so before animation starts, i remove the sprite with :</p>
  
  <pre><code>[b_pic.parent removeChild:b_pic cleanup:YES];
  </code></pre>
  
  <p>and then i am trying to add it back, BUT its crashes. i add it with :</p>
  
  <pre><code>b_pic=[CCSprite spriteWithFile:@"regular.png"];
      b_pic.position=ccp(160,175);
      [self addChild:b_pic];
  </code></pre>
  
  <p>what am i doing wrong here ?
  i cant understand this child and parent thing.</p>
  
  <p>i have also tried to remove the sprite with :</p>
  
  <pre><code>[self removeChild:b_pic cleanup:YES];
  </code></pre>
  
  <p>thanks a lot .</p>