I am unable to make a new directory in an existing directory that is one level up from where my script is located. Here's my folder structure:

Code:
html
     > api
          > script.php
     > clients
          > [WHERE I WANT TO CREATE A FOLDER]
I've tried using chdir("../clients") prior to running mkdir("./newfolder") but I get some strange error. Is that even how I should do this?

Racking my brain on this one...

Thanks everyone.