Cannot place imported round top window in wall

[BB boy]

Pro-10.
The Library of available windows w/round top isn't what I want. I imported the one I like from 3D warehouse. Saved the skp to my skp folder. Opened my plan and did a drag and drop (the only way I know how to do it) to place the window in plan. The window is now in my plan. I opened it and sized it apporpriately, however; when I try to drag it into the wall, even using the ctrl drag method it keeps jumping back out as in the pics. I tried deleting the previously installed window first of course, but it refuses to stay in the wall. I tried placing a window from those available with the soft ware, and then selecting the type from my skp file, but that option is not available.

Thoughts/Ideas?