Try placing the ellipse block, I am assuming you have it as a drawing IE ellipse.dwg, in a folder that is on the search path.
For your search path go to options, files, support file search path. Use one of those folders or add one.
A much better option is to use mleader and set one up for the ellipse, have that in your template drawing. You can drag and drop mleader styles into any drawing from the Design Center.