Identical code presenting different results

I have been following through the Tanks! tutorial and seem to have hit a snag. Below are two blocks of code, which through all tools I have used appear as though they should compile identically. However, the first does NOT update the =_AimSlider.value but the second does... If I copy and paste JUST the Update function from 2 to 1, it works... the second example is the pre-completed version so I REALLY want to know what I have done wrong. I THINK it is an underlying linespace issue but I get no warnings and can't fix it :/.

1. My version

   private void Update() { // Track the current state of the fire button and make decisions based on the current launch force. m_AimSlider.value = m_MinLaunchForce; // Set slider value to minimum possible initially.

     if (m_CurrentLaunchForce >= m_MaxLaunchForce && !m_Fired) // At max charge, not yet fired...
        {
            m_CurrentLaunchForce = m_MaxLaunchForce; // So we set the launch force to the maximum so it cannot be over max charge.
            Fire(); // Then call the fire function to fire the shell.
        }
   
        else if (Input.GetButtonDown(m_FireButton)) // Have we pressed fire for the first time?
        {
            m_Fired = false; // We know the button has just been pressed to we have not fired yet.
            m_CurrentLaunchForce = m_MinLaunchForce; // We also know that the launch force will (or should) be at it's minimum value, so we set that as well.
   
            m_ShootingAudio.clip = m_ChargingClip; // Sets the current audio clip to play, as the charging clip as we have just started holding shoot (hence charging a shot).
            m_ShootingAudio.Play(); // Play the charging sound.
        }
   
        else if (Input.GetButtonDown(m_FireButton) && !m_Fired) // Holding the fire button but not yet fired.
        {
            m_CurrentLaunchForce += m_ChargeSpeed * Time.deltaTime; // Set the current launch force to equal it's current value plus charge speed * time held.
   
            m_AimSlider.value = m_CurrentLaunchForce; // Update the arrow shape/size to match the current launch force.
        }
   
        else if (Input.GetButtonUp(m_FireButton) && !m_Fired) // We released the button, having not fired yet.
        {
            Fire(); // Fire button has been released so we simply call the fire function.
        }
    }
   
   

2. Example version

private void Update () { // The slider should have a default value of the minimum launch force. m_AimSlider.value = m_MinLaunchForce;

         // If the max force has been exceeded and the shell hasn't yet been launched...
         if (m_CurrentLaunchForce >= m_MaxLaunchForce && !m_Fired)
         {
             // ... use the max force and launch the shell.
             m_CurrentLaunchForce = m_MaxLaunchForce;
             Fire ();
         }
         // Otherwise, if the fire button has just started being pressed...
         else if (Input.GetButtonDown (m_FireButton))
         {
             // ... reset the fired flag and reset the launch force.
             m_Fired = false;
             m_CurrentLaunchForce = m_MinLaunchForce;

             // Change the clip to the charging clip and start it playing.
             m_ShootingAudio.clip = m_ChargingClip;
             m_ShootingAudio.Play ();
         }
         // Otherwise, if the fire button is being held and the shell hasn't been launched yet...
         else if (Input.GetButton (m_FireButton) && !m_Fired)
         {
             // Increment the launch force and update the slider.
             m_CurrentLaunchForce += m_ChargeSpeed * Time.deltaTime;

             m_AimSlider.value = m_CurrentLaunchForce;
         }
         // Otherwise, if the fire button is released and the shell hasn't been launched yet...
         else if (Input.GetButtonUp (m_FireButton) && !m_Fired)
         {
             // ... launch the shell.
             Fire ();
         }
     }