3D Soda Can Modelling Scaling Issue *Beginner*

[mccormick789]

I am a beginner student to Maya 2014 and am following a tutorial on 3D modelling.(https://www.youtube.com/watch?v=EY4-JmuczxM) at 8:30 in the tutorial is where my problems begin. He starts by extruding the top face of the soda can, which I was able to do. But when I go to scale the top rim of the soda can it simply does not work. I am a beginner so the possibility of me accidentally changing a setting is likely, but I need feedback on how to use it again. I have tried resetting the scale tool settings, but when I go to press R to scale I cannot. If somebody could please review the file attached and offer some feedback it would be much appreaciated 

[Maxya]

 I have no idea why you cant do this,

I check your model and try to scale the top rim,

it doesn't have any problems.

I guess when you try to do this step,

you also select other faces in back side,

(check your model at back side, geomatry is not good)

so you cant get the same result

I suggest you to do this,

double click the " select tool " in tool box,

go to " tool settings "

check the " camera based selection " option