Linux – Mounting CIFS filesystems: error -1 opening credential file

I'm trying to permanently mount a windows server share via fstab and netfs on a CentOS 5.x box.

I can successfully mount and access the share via the following command:

mount.cifs //winserver.addomain.int/shared /mnt/foo --verbose -o rw,-dom=addomain,credentials=/opt/foo2/etc/cred.file,dir_mode=0775,file_mode=0664,soft

That works fine.

So then I unmounted it and added the following line to /etc/fstab:

//winserver.addomain.int/shared    /mnt/foo     cifs     rw,-dom=addomain,credentials==/opt/foo2/etc/cred.file,dir_mode=0775,file_mode=0664,soft     0     0

And when I run service netfs start I get the following error:

Mounting CIFS filesystems: error -1 opening credential file 

For security purposes, I've set owner and group for the credential file to root:root and file permissions to 0400

I'm running all commands (both mount test and netfs start command) as root user so I don't see why there's a permission issue.

I've also tested this procedure on another box (with a different share) and it works fine.

Can someone tell me if there are any netfs debug logs I can check here? What else can I do to troubleshoot?