IIRC you can't connect target-action on custom views. It only works with Apple-provided views and subclasses thereof (so if your view was a subclass of NSControl, it would work). However, you can always call setTarget: and setAction on your view in the awakeFromNib (or equivalent) method of whatever object owns the NIB.
If your class is already a subclass of another Apple-class that supports target/action, there is probably a syntax error somewhere in your code, or an #if/#ifdef or the like that makes the Interface Builder part of Xcode unable to correctly parse your class. In that case it often leaves it out, and you get none of its IBOutlets listed.