CALayer Undefined symbols error

I am trying to use a CALayer to make a bottom border on a text field. The problem is when I build I get this error. I added the Quartz framework to my app.

Undefined symbols for architecture armv7:
  "_OBJC_CLASS_$_CALayer", referenced from:
      objc-class-ref in StatusViewController.o
ld: symbol(s) not found for architecture armv7

Code is like this.

CALayer *bottomBorder = [CALayer layer];
bottomBorder.frame = CGRectMake( 0.0f, nameTextfield.frame.size.height - 1, nameTextfield.frame.size.width, 1.0f );
bottomBorder.backgroundColor = [UIColor blackColor].CGColor;
[nameTextfield.layer addSublayer:bottomBorder];

What could the problem be?