mspaint - copy won't transparent!

[surface9]

I make an exact copy of a *.bmp photo and use the path tool (jagged
outline) to select a portion of the cloned photo, then I deselect
"draw opaque" as well as clicking on the little "transparent" box
(below the toolbox). As long as I copy my selection to the same bmp
from which I selected it, then transpanency works and the white areas
(supplied to make a rectangle around my jagged selection) are
transparent. BUT, when I switch to the original photo, and deselect
"draw opague" there also as well as clicking on the "transpanent" box
also, then when I paste (from the clipboard), my copied selection IS
NOT TRANSPARENT! I checked the color value of the white areas used to
complete the rectangle, and the value is 252, but, over on the cloned
one, where I made the selection and then pasted it, the white areas
are 256. WHAT GIVES HERE? Why does mspaint reduce the color value of
the fill character from 256 for the photo from which I made the
selection and copy, down to 252 for any other photo that I copy it
to? It makes it impossible to copy a jagged-outlines area from one
photo to another, unless you can go change that 252 fill color back to
256 - why would mspaint, or the clipboard????, do that?

STUMPED, BEFUDDLED, and OUT OF OPTIONS HERE.

This happens on win98se, win2k and winxp.