Always run testparm
Maybe one of the most important tools we have. The testparm utility checks if the the smb.conf is valid. Run
# testparm -s
If somone provided you with a smb.conf file use:
# testparm -s /path/to/smb.conf
If modifications are done to a smb.conf file you should always run testparm to verify it is correct!
Also if you're repoting a bug please always share the output of testpam -s