won't move part anymore part just floats?? :/

the part is just stuck in the air, it won't fall??

local MainPart = game.Workspace.Part
local TextBox = script.Parent

local function CheckIfCompatible(txt)
    local max = 10

    if string.len(txt) >= max then
        return false
    end

    if string.len(txt) <= max then
        return true
    end
end

TextBox.FocusLost:Connect(function()

    local texts = ""

    local text = TextBox.Text
    local Compatible = CheckIfCompatible(text)

    if Compatible then
        MainPart.Position = Vector3.new(0, text, 0)
        texts = "Moved Part"
    else
        texts = "Too long to read."
    end

    script.Parent.Text = tostring(texts)
end)