That hasn't been updated in a while, which may be the issue. They changed some aspects of the commands used for click-to-cure, and that window was most likely not updated to reflect that.
On the other hand, it may not be loading at all. Are you seeing the extra buttons and what not in game? If not, check and make sure that both your mods are in the same folder and that the group window file is just inside that (IE its directly in UI\UIAddons\ and not in a subfolder of that).
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