If the form's Picture property is set to a back ground picture (even
if the picture is just a color), it will over-ride any form back color
property setting.
Check the form's picture property (on the Format tab). It should be
set to (none). If it is set to a picture, delete the value. Answer Yes
when asked by Access if you really want to delete the value.
Then you can set each section of the form's back color.