Failing to backup a file newly amended, since first and only backup

I have a new Passport Essential which I have just successfully used to back up my data from the computer hard drive for the first time.  I might add it took over night to complete but hey ho it did it.

Leaving it plugged in, I worked on a .xls file today and saved as normal.  Clicking the disk icon.  Now having viewed the WD Software it gives me an error message that reads. 

Object reference not set to an instance of an object.'


I assume this means it couldn’t find the file.  Why?  I haven’t moved it, simply saved it in the same location it was in when the PE did the original backup.  PUZZLED?  How can I now back up this amended file.

Thank you


Try downloading the newest version of SmartWare and see if that helps you.