Solution:
Its not PHP source code. You recently opened that php in program, so what you posted is that PHP script yield. You should open genuine .php document in some editorial manager, and show us the source code 🙂
By your inquiry – This isn’t blunder, its admonition about calling the variable, which isn’t set on some point. So your content actually works, yet conceivably your structure has wrong field name to send, so your php script can’t figure out what information you want to look for, in light of the fact that can’t view that as explicit variable.