php notice displayed when moodle installer can't write to the data directory

Installing Moodle and Moodle doesnt currently have write permission to the data directory. I get the following php notice displayed.

Notice: Undefined variable: a in /home/andrew/Desktop/review/moodle/install.php on line 320
Call Stack

1. Time Memory Function Location
   1 0.0021 443200 {main}

   ( ) ../install.php:0

Under the data directory text box is the following message:
Data directory ({$a->dataroot}) cannot be created by the installer.

The $a isnt being substituted.