Default Roblox cursor texture?

I can see that you accidentally wrote the asset ID incorrectly. You forgot about the “/” after asset in “http://www.roblox.com/asset/?=

What I do suggest is replacing the old asset format with the new one here:

Mouse.Icon = "rbxassetid://[ID]"

It will save you time writing “http://www.roblox.com/asset/?=” over and over for the future