I am making bubbles shooter game in cocos2d

I have taken one array in that i have inserted number of different color bubbles and i showing on my game scene also , but if give some move action to that array ,it moving down but it displaying all the bubbles at one position and automatically destroying , what is the main reason behind this please help me

here is my code:

-(void)addTarget {
    CGSize winSize = [[CCDirector sharedDirector] winSize];

    //CCSprite *target = [CCSprite spriteWithFile:@"3.png" rect:CGRectMake(0, 0, 256, 256)]; 

    NSMutableArray * movableSprites  = [[NSMutableArray alloc] init];
    NSArray *images = [NSArray arrayWithObjects:@"1.png", @"2.png", @"3.png", @"4.png",@"5.png",@"1.png",@"5.png", @"3.png",  nil];       
    for(int i = 0; i < images.count; ++i) {


        NSString *image = [images objectAtIndex:i];
        // generate random number based on size of array (array size is larger than 10)

        CCSprite*target = [CCSprite spriteWithFile:image];
        float offsetFraction = ((float)(i+1))/(images.count+1);
        //target.position = ccp(winSize.width*offsetFraction, winSize.height/2);
        target.position = ccp(350*offsetFraction, 460);
        //  [[CCActionManager sharedManager ] pauseAllActionsForTarget:target ] ;


        [self addChild:target];
        [movableSprites addObject:target];

        //[target runAction:[CCMoveTo actionWithDuration:20.0 position:ccp(0,0)]];
        id actionMove = [CCMoveTo actionWithDuration:10 position:ccp(winSize.width/2,winSize. height/2)]; 
        id actionMoveDone = [CCCallFuncN actionWithTarget:self selector:@selector(spriteMoveFinished:)];
        [target runAction:[CCSequence actions:actionMove, actionMoveDone, nil]];

        }
}

after the move at certain position i want to display all the bubbles in centre of my window