Back Up from Dropbox to WD My Passport Ultra won't work

Was trying to backup my dropbox files into the external drive but it doesn’t work. Only two folders were backed up then it stopped. Now everytime i try to back up the other files manually, i get this error message at my toolbar. 

“Destination cannot be auhthenticated. please verify your information.” 


Some help? 

Hello ChristianJay, welcome to the WD Community. What version of Smartware you have installed?