How to use a custom conditional compilation symbol with Visual Studio 2017?

Question

In VS2017 I have defined a conditional compilation symbol 'APPSTORE'.

However the compiler is not recognizing the symbol. Notice the APPSTORE code is disabled.

What is the proper way to use conditional compilation symbols?

Instead of a semicolon, I have tried a comma as well...

APPSTORE,__UNIFIED__;__MOBILE__;__IOS__;

Answer 1

The code I was trying to control was in a different assembly than the assembly where I set the conditional compilation symbol. Once I entered the symbol in the correct project, it behaved as expected. Thanks to @SushiHangover!