You need to combine your shapes together first, select the shapes and then Hold the Ctrl key and tap the L key this will combine your shapes then the join nodes should work.
On CorelDRAW, I learned vector graphics, and because of "workflow" problems, it made learning Illustrator a little complicated-that is, things just work differently. These days, I'm concentrating a little more on Illustrator simply because it has such a wide industry influence that you need to be able to use it.
The only "downside" that I see is in file accessibility, where you really need Illustrator open. The import / export cycle for opening a.ai file in CorelDRAW is often clunky, but I haven't checked it much in newer versions, to be honest. Moving your .ai job to Flash is one region where Illustrator wins hands down. CorelDRAW does not support the, atm, fxg file format.