Problems mounting an SMB share in my fstab

Install smbfs.

Sounds silly that a package could fix this but when you use credentials files, the kernel diverts to the mount.cifs command rather than doing the mount itself. This package provides mount.cifs so should get you on the road to victory!

Edit: As Klaus points out in the comments, for 13.04 and later, you need cifs-utils.

I went mad on 14.04. the credential= option was not mounting the share in fstab although I could mount it "by hand" in the cli. Issue was that the "cifs-utils" package was not installed...

sudo apt-get install cifs-utils

and everything was fine...