mkdir() says theres no such directory and fails?

Question

Im likely doing something very simply wrong, but when I try to make a directory (using a variable of an insert just performed as the last folder name), I get the error:

Answer 1

Probably the real error was that he forgot an extra apex.

This:

mkdir("images/listing-images/rent/'.$insertID.");

Inside:

/'.$insertID."

Correct Version:

/".$insertID

Extended Correct Version:

mkdir("images/listing-images/rent/".$insertID);