Won't Let Me Resize Objects

Hi, I just downloaded the game last night and it will not let me size up and down objects. I have a Mac laptop. I tried using the shift + [ ] keys with the object selected and nothing happens. I also tried the shift + ( ) keys for pc just to see if it would work. I even checked the keyboard settings on my laptop and my keyboard settings were already set to US and there is no UK option for keyboard settings on my laptop. I am officially at a loss as I have tried all of the troubleshooting for this issue that I could find. 

please help