So the box and all shows but the text does not change. I use a text button to activate the shout and a text box on the gui to create a shout.
local Text = script.Parent.Shout.Shout.Text
local Button = script.Parent.ShoutBox.TextButton
local SText = script.Parent.ShoutBox.TextBox.Text
local Frame = script.Parent.Shout
Button.MouseButton1Click:connect(function()
script.Parent.Shout.Shout.TextScaled = true
Frame.Visible = true
Text = SText
wait(5)
Frame.Visible = false
script.Parent.Shout.Shout.TextScaled = false
end)

2 comments
SText.Text?
Look at the local things at the start they tell you what Text and SText are