User color choice not saved in export preset?

Question

I'm currently writing my first plugin and still in a learning curve.
My export plugin has a color_well control to choose a color. I have defined a default value of LrColor(1,1,1) which works well.
However, the chosen color is not saved so every time the export dialog is used, it comes up with the default color value and the previously chosen color is lost.
What am I doing wrong?
Thanks,
Mario
Code snippet:
myPlugin.exportPresetFields = {
    { key = 'borderColor', default = LrColor(1,1,1) },
    ...more keys
function myPlugin.sectionForFilterInDialog( viewFactory, propertyTable )
    return {
        viewFactory:row {
            viewFactory:color_well {
                value = LrView.bind('borderColor'),
end

Answer 1

Many thanks for the reply and sorry for the delay. It took me DAYS to figure out how to save the r,g & b components.
Finally, I succeeded with this method:
myPlugin.exportPresetFields = {
    { key = 'color_r', default = 1 },
    { key = 'color_g', default = 1 },
    { key = 'color_b', default = 1 },
function myPlugin.sectionForFilterInDialog( viewFactory, propertyTable )
    return {
        viewFactory:row {
            viewFactory:color_well {
                value = LrView.bind({
                     key = 'borderColor',
                     transform = function ( value, fromTable )
                          if fromTable then
                              return LrColor(propertyTable.color_r, propertyTable.color_g, propertyTable.color_b)
                          else
                              propertyTable.color_r = value:red()
                              propertyTable.color_g = value:green()
                              propertyTable.color_b = value:blue()
                              return LrBinding.kUnsupportedDirection
                          end
                     end
end