Problem with menuItem content size

Hi , im new in cocos2d-x , i think its a great framework and im trying to make videogames with it.

I have got a problem with contentsize , i create a menuitem , and then i add a sprite child.
When i try to set the contentsize manually , the menuitem work but in a wrong way ,
touching work outside and inside of the sprite.
I think im doing something wrong , i hope someone can help.

// Create Tab Item
pTabItem = NULL;
pTabItem = CCMenuItem::create( this , menu_selector( TMOMenu::menuTabCallback ) );
pTabItem~~>setPosition);
// Create Sprite
pTabSprBg = NULL;
pTabSprBg = CCSprite::create~~>xPathF );
pTabSprBg~~>setPosition );
// add child
pTabItem~~>addChild( pTabSprBg , 100 );

// Set menuitem content size
pTabItem~~>setContentSize.width , pTabSprBg~~>getContentSize().height ) );

// add child
pMenu->addChild( pTabItem , 100 );