WD MyBook World Edition + EMC Retrospect Backup Software

Hi, 1st off i have to say i'm very impressed with the WD MyBook World edition NAS, its fast, quiet, huge capacity, has lots of features, and looks pretty cool too. Although i'm not actually using the Anywhere Access it is nice to have should i want to access my files from the office or abroad.

Now onto my question, i'm trying to setup the EMC Retrospect software so that it backs-up my files to the mapped network share i created on the MyBook. As you would imagine it prompts for a username and password to access the drive, which i gave it. But for some reason it just refused to accept the username and password. I have checked and checked again the details, and they are 100% accurate. Windows accepts the login details and connects no problem, so why will Retrospect not let me in?

Does anyone have a similar setup, who can offer some advice?

PS. I know i could use some alternative software but the bundled EMC Retrospect does look the business so i would like to pursue this. Ta.