Why can I not use predefined constants in .rc file?

I want to make sure one cannot mix up 64 and 32 bit version of my DLL file. This is why I defined following preprocessor constant in the project properties:

In my .rc file, I have these lines:

#ifdef x64 
  #define MY_PRODUCT_NAME = "My file 64bit"
#else
  #define MY_PRODUCT_NAME = "My file 32bit"
#endif

I want to use these constants in resource block below:

BEGIN
    BLOCK "StringFileInfo"
    BEGIN
        BLOCK "000904b0"
        BEGIN
            VALUE "CompanyName", "SOMENAME"
            VALUE "FileDescription", "WHAT THIS FILE IS"
            VALUE "FileVersion", "1.0.0.1"
            VALUE "InternalName", "file.dll"
            VALUE "LegalCopyright", "Don't sell it pls"
            VALUE "ProductName", MY_PRODUCT_NAME
        END

On the line containing MY_PRODUCT_NAME, I get this compiler error:

1>  
1>StopThat.rc(58): error RC2133: unexpected value in value data
1>  
1>  
1>StopThat.rc(58): error RC2132: expected VALUE, BLOCK, or END keyword
1>  

This makes me real angry, because that's exactly what microsoft does in their documentation .

Am I doing something wrong? I guess I am, so what is it?