I can mount the drive in the following way, no problem there:

mount -t cifs //nas/home /mnt/nas -o username=username,password=pass\!word,uid=1000,gid=100,rw,suid

However if I try to mount it via fstab I get the following error:

//nas/home /mnt/nas cifs  iocharset=utf8,credentials=/home/username/.smbcredentials,uid=1000,gid=100  0        0 auto

.smbcredentials file looks like this:

username=username
password=pass\!word

Note the ! in my password ... which I am escaping in both instances

I also made sure there are no eol in the file using :set noeol binary from Mount CIFS Credentials File has Special Character

chmod on .credentials file is 0600 and chown is root:root file is under ~/

Why am I getting in on the one side and not with fstab??

I am running on ubuntu 12 LTE and mount.cifs -V gives me mount.cifs version: 5.1

Any help and suggestions would be appreciated ...

UPDATE: /var/log/syslog shows following

[26630.509396] Status code returned 0xc000006d NT_STATUS_LOGON_FAILURE
[26630.509407] CIFS VFS: Send error in SessSetup = -13
[26630.509528] CIFS VFS: cifs_mount failed w/return code = -13

UPDATE no 2

Debugging with strace mount through fstab:

strace -f -e trace=mount mount -a
Process 4984 attached
Process 4983 suspended
Process 4985 attached
Process 4984 suspended
Process 4984 resumed
Process 4985 detached
[pid  4984] --- SIGCHLD (Child exited) @ 0 (0) ---
[pid  4984] mount("//nas/home", ".", "cifs", 0, "ip=<internal ip>,unc=\\\\nas\\home"...) = -1 EACCES (Permission denied)
mount error(13): Permission denied
Refer to the mount.cifs(8) manual page (e.g. man mount.cifs)
Process 4983 resumed
Process 4984 detached

Mount through terminal

strace -f -e trace=mount mount -t cifs //nas/home /mnt/nas -o username=user,password=pass\!wd,uid=1000,gid=100,rw,suid
Process 4990 attached
Process 4989 suspended
Process 4991 attached
Process 4990 suspended
Process 4990 resumed
Process 4991 detached
[pid  4990] --- SIGCHLD (Child exited) @ 0 (0) ---
[pid  4990] mount("//nas/home", ".", "cifs", 0, "ip=<internal ip>,unc=\\\\nas\\home"...) = 0
Process 4989 resumed
Process 4990 detached