Pen color doesn't work under Delphi 3

Hi,

        I have a problem with the pen.color property of a bitmap, see this
sample code:

In Formcreate:

MyBMP := TBitMap.Create;
MyBMP.LoadFromfile('c:\winnt\winnt256.bmp'); (* a 256 color bmp *)

In Button1CLick:

MyBMP.Canvas.Pen.Color:=$0000FFFF; (* pure yellow *)
MyBMP.Canvas.MoveTo(0,0);
MyBMP.Canvas.Lineto(100,100);
MyForm.Canvas.Draw(0,0,MyBMP);

        It doesn't work fine because I obtain a line, but it's not yellow.

Note 1: my display is set to 64K colors, so the problem isn't that I
have too few colors.
Note 2: the same code works fine in Delphi 1 running in the same
computer, I'm now working
        with Delphi 3.
Note 3: if I load a 16 color BMP instead of the 256 colors one It works
fine.
Note 4: The same problem appears if I run my application under W95 (is
not a NT problem).
Note 5: I've tried changin the first byte of the color "00" with "01"
and "02" without results.

        Does anybody know what happens?