"Invalid GlassFish domain" when adding server to Eclipse

[P Dworkin]

JRE 7
Eclipse Version: Juno Service Release 1, Build id: 20120920-0800
GlassFish 3.1.2.2

I downloaded GlassFish from http://www.oracle.com/technetwork/java/javaee/downloads/index.html,
installed at "/Users/adminuser/dev/java/glassfish3" and got the server running.

Installed the GlassFish plugin in Eclipse. Tried to add a new server. Specified the path
"/Users/adminuser/dev/java/glassfish3/glassfish/domains/domain1" as the domain Directory and got the error
"Invalid GlassFish domain"

Anyone suggest what I'm doing wrong?

Thanks!