XF 1.3 Tiagachat pro 1.3 issues

hi all, i installed as told to and as i do all other addons without any issues, but this addon im having issues with, i cant install this, it comes up with this message..... Callback Dark_TaigaChat_EventListener_Listener::LoadClassModel is invalid (Invalid Method).

i even uninstal and then install the old version and it works fine