HTTP 400 (HTTP/1.1 400 Bad Request)..?

I've been trying to fix this for HOURS.. about to explode. Please help.

Error ; HTTP 400 (HTTP/1.1 400 Bad Request) 15:42:45.729 - Script 'Players.Player.PlayerGui.ScreenGui.TrelloAPI', Line 424 - method AddCard 15:42:45.730 - Script 'Players.Player.PlayerGui.ScreenGui.RentB.Submit.3', Line 5 15:42:45.731 - Stack End

ap = require(script.Parent.Parent.Parent.TrelloAPI)
local Board = ap:GetBoardID("Primitive") 
local List = ap:GetListID(script.Parent.Parent.TextBox.Text,Board) 
function trello()
ap:AddList(script.Parent.Parent.TextBox.Text,Board)
ap:AddCard("What place do you want to rent out?","Place : "..script.Parent.Parent.Place.Text,List,"")
end
script.Parent.MouseButton1Down:connect(trello)

Looks to me that AddCard isn't a thing, and it errors when you try to run it because of that.