Change rating in cull window

Hi,

I have the following script that when run increases rating of the selected image or images:

tell application "Capture One"
    set selectedVariants to selected variants
    if selectedVariants is {} then
        display dialog "No images selected."
    else
        repeat with theVariant in selectedVariants
            set currentRating to rating of theVariant
            if currentRating < 6 then
                set newRating to currentRating + 1
                set rating of theVariant to newRating
                exit repeat
            end if
        end repeat
    end if
end tell

However, it does not work in the Cull Window, as the selected variant  always correspond to the image selection in the main window of capture one. And this selection is the one getting the rating changed, not the selection within the Cull Window. 

Can anyone help me to get this to work, both on the main window, and in the cull window?

Thank you in advance.