"generate-pch command failed with exit code 1" when making a new Xcode scheme

I'm following the instruction here http://www.teratotech.com/blog/xcode-7-steps-to-easily-switch-between-multiple-environments/ to generate different schemes for different environments..

I created a testing configuration and created a new scheme to use that configuration. However, when I build and run, I'm getting this error:

<unknown>:0: error: generate-pch command failed with exit code 1 (use -v to see invocation)

 error: 'AFNetworking/AFNetworking.h' file not found
#import <AFNetworking/AFNetworking.h>

1 error generated.
<unknown>:0: error: failed to emit precompiled header '/var/folders/f2/6j4b4kz54xy1vf_2gdlnrllc0000gn/T/My-Project-Header-47bffb.pch' for bridging header '/Users/me/Dev/my-project/My-Project-Header.h'

When I build with my original scheme, everything's fine... I only have 1 target. Am I missing anything?

EDIT: I'm using Cocoapods to manage my dependencies, if that makes any difference.