Also, if you have a firewall such as shorewall installed by default (I'm not sure what comes with redhat) then it may have ports closed that would normally be open. You'll have to check out if you have a firewall program/script running and if so, where you can edit it.
and see if swat is running. Some distros install swat with samba, others don't. You also have to edit /etc/services to enable swat, or add the entry if it doesn't exist. Read the manpage for swat and it will show you an example of this, or refer to Dani's tutorial (I think she has it in there...)
If swat isn't running, then port 901 won't be listening, which will give you the error you received.