C language in Visual studio Struct within a struct: error CXX0025: Error:operator needs class/struct/union

Hopefully someone can tell me what I'm doing wrong.
I have a struct that contains a struct. When I try to access properties of the struct contained
within the first struct, I receive an error:
 CXX0025: Error:operator needs class/struct/union

From what I can tell this is proper syntax in C; however, there must be something specific
to the Microsoft C++ compiler that I'm not getting.
I created a win32 project in visual studio 2008.

Thanks.

void testStructConcept()
{      
      struct first_structure_type
      {
            int integer_member;
            float float_member;
      };
 
      struct second_structure_type
      {
            double double_member;
            struct first_structure_type struct_member;
    };

    struct second_structure_type demo;
 
      demo.double_member = 12345.6789;
      demo.struct_member.integer_member = 5;
      demo.struct_member.float_member = 1023.17;
}