Palette in DirectX

Hi,guys

If i've initialized the palette[256] and attach it to the primary surface.
if I set one palette as
PALETTEENTRY red = {255,0,0,PC_NOCOLLAPSE};
and use it to change one entry of the original palette[256],

lpddpal->SetEntries(0,0,1,&red);
I think this fucntions means to change the first entry to red.

and it will change the screen to red.(actually it works)

but if i change the 2nd entry to red:
lpddpal->SetEntries(0,1,1,&red);

then only black on the screen.so my conclusion is that it only shows the 1st entry.

Could anyone tell me whether i am right and why this happend.
Thanx!!!