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.