GD.pm: Color set with colorAllocate doesn't set correct color

[utoyo]

I am opening an image with NewFromJpeg and then use $newcolor = $im->colorAllocate(X,Y,Z) to set the color. But when I use $newcolor with the polygon function, the color that is actually set is a color from the image (a color in a good amount of the image) and not the value I chose.

What could I be doing wrong? Can the colorAllocate function be used with truecolor images? If not, what should I be using?

Thanks in Advance.