No writable partition

I have a passport essential. I am trying to set it up for a mac lap top with OSX 10.5.2. I can get up a dialog box which shows a column bar with things in it for the computer side but the passport essential side says “No writable WD Smartware Partition found”. If I try to run backup I can get a box that says drive erase or cancel. Neither of these seem to make any difference. I have tried turning off the computer, plugging the passport in and turning it on again. That has made no difference. The box I got says it works with a mac but I am beginning to wonder.  Cannot believe this is so complicated. Why is this so massively more difficult than a normal flash stick?  

The drive that you have is compatible with both a Mac and a PC. However, this drive comes default formatted for a Windows based computer and you will need to format it on your Mac so that your Mac can use it. Flash sticks are smaller in capacity than drives so they usually use a file system that both Mac and PC can use. However, there are limitations to the file systems used by flash sticks. I included a link below on how to format the drive so that it will work on your system.

How to partition and format a WD drive on Windows (7, Vista, XP, 2000) and Mac OSX