Enums - probably an old subject

[Steve Teale]

import std.stdio;

enum Intention
{
    EVIL,
    NEUTRAL,
    GOOD,
    SAINTLY
}

void foo(Intention rth)
{
    if (rth == EVIL)
       writeln("Road to hell");
}


void main()
{
    foo(EVIL);
}


Why does the compiler complain in both places about EVIL. Can it 
not work out which EVIL I mean? There's only one choice.