CCSprite setScale() BAD_ACCESS Error

cocos2d-x C++
#1

I am trying to change the scaling of a certain sprite. I have a Balloon class which has a CCSprite in it called m_BalloonSprite. It has a method called startTimer like this:

void Balloon::startTimer( ) {
   this -> m_BalloonSprite -> schedule( schedule_selector( Fruit::startGrow ), 1.0 );
}

And a startGrow method like this:

void Balloon:startGrow( CCTime dt ) {
   someVariable++;
   this -> m_BalloonSprite -> setScale( 0.10 * someVariable );
}

However, I’m getting EXC_BAD_ACCESS errors whenever I try to run it. By the way, Balloon is a custom class I made.

Thanks in advance.