I am running JMS Multisites 1.2.68 on Joomla! 1.7.3 and trying to create a new site. I have verified that the directory for the slave site (jms17_slave4) does exist, and I specify the full path to the slave directory under "Deployed directory:" on Site Details. The Site ID (jms17_slave4) exactly matches the name of the "Deployed directory:"

However, whenever I click save I get the error,

The deployed directory [/mnt/web/cms/jms17_slave4] does not exists.

If you are sure that the directory physically exists and that you receive an error that report that the directory does not exists then verify the permission and ownership of the folder to be sure that you are autorise to access this directory.

Perhaps that the permission of the directory is forbidden.

I will check the permissions although I believe they are correct as well.

Additional: the above error message is received in Mozilla. In Internet Explorer, the error is:

-1 - An error has occurred.
Unable to create target folder

It was a permissions problem after all! Actually, it was an ownership issue. After resolving that, I was able to create the slave site.