Time Machine

Hey there. I have been using a lacie external hard drive for my time machine backups for like a year now. I just bought a new bigger hard drive which I was thinking to switch the backups to. So I went into the pref. pane and switch the drives. Now I want to switch back i keep on getting an error message of which I took a screen shot. How can I get it to work properly?

Thanks in advance for the advice

Is the disk formatted as HFS+? It looks like somehow the permissions got messed up on that drive. Reformatting should do the trick, but it not, open up terminal and try this command:

sudo chown -R `id -un`:`id -gn`/directory

replace directory with the path to your time machine drive, such as /Volumes/Time\ Machine

thanks for the response, however the drive still has my backups so i dont want to format it and lose all my info on it.