[fpc-pascal]Problem with CASE statement

[Lubomir.Cabla at cssz.cz]

In go32v2 i got a problem with case statement.
With compiler 1.0.10 is this without errors:

const kbDown = $5000;
      kbUp   = $4800;
var ch : char;
begin
  ch:=ReadKey;
  case ord(ch) of
    Hi(kbDown): writeln('kbDown');
    Hi(kbUp)  : writeln('kbUp');
  end;
end.

New FPC compiler 1.9.3 produced error 'duplicate case label'.

With these commands i found that function HI produced 0 for both constants.

  writeln(HexStr(Hi(kbDown),2));
  writeln(HexStr(Hi(kbUp),2));

OK i changed definition of kbDown and kbUp to

const kbDown : word = $5000;
      kbUp   : word = $4800;

and now Hi(kbDown) return $50 etc. but with compilation
i got another error 'Constant Expression expected'.

I know what this is but i don't understand why.

Maybe somebody help me ?

This definition 'const kbDown = $5000;' produced word or logint or ... ?

Lubomir Cabla