How to fix "Profile is not closed" in ST6?
You must use the constraints in the relate tab. In your particular case, try the link constraint (I'm not sure about its name in the English version of SE interface. Have a look at the attached image).
You can also have a look at this video clip: https://www.youtube.com/watch?v=lwvUZ1Q52vg
Answered with a tutorial: https://grabcad.com/tutorials/how-to-fix-profile-is-not-closed-in-st6