Attempt to call a nil value?

So, I'm currently making a script executor for in roblox game. (YES I enabled loadstring in my game) and what I'm doing is when you click execute, it's suppose to load it, but the problem is, I keep getting this error "Attempt to call a nil value"

function onClicked(GUI)
loadstring(script.Parent.Execute.Text)()
end
script.Parent.Execute.MouseButton1Click:connect(onClicked)

Here is full script: prnt.sc/jhfhtj Here is how my gui looks like: prnt.sc/jhfi4u here is my error: prnt.sc/jhfibk Another view of my error: prnt.sc/jhfj6x