Can someone help me fix this?

This is in a GUI. I want this script to take what the player types in the text box and put it at the end of the link "http://www.roblox.com/asset/?id=" and finally paste the link in the SoundId property of the Sound object. I tried the script below. But it doesn't seem to work.

local Button = script.Parent
Frame = script.Parent.Parent.Parent
a = script.Parent.Parent.AudioIDInsert.Text		

function onClick() 
		game.Workspace.RadioModel.Music.Script.Sound.SoundId="http://www.roblox.com/asset/?id=" .. a
		wait(0.1)		
		Frame:Destroy()
end
		
Button.MouseButton1Click:connect(onClick)