fstab mounts Windows share as read-only

In attempt to access my home shared folder on my Windows 2003 Server / Active Directory domain, I’ve stuck following entry in my /etc/fstab file:

//server/share$ /home/username/domainshare smbfs credentials=/home/username/.credsfile,workgroup=windows.domain.com,defaults 0 0

I can view the folder, subdirectories, and contents, but everything is “Read Only”. Is there a parameter I’m missing in the fstab file? I didn’t find anything obvious in the man page.

I’ve posed this same question on LinuxQuestions but with mixed results. See http://tinyurl.com/rend8 if you’re interested in other suggestions I’ve had with this problem.