Groove not showing in 3D

[M3 Euro LTW]

1) I've tried to make an object with a groove, but in 3D, it says "one line not shown accurately" or something. IE, the groove doesn't show up.

Side and top views confirm that a groove is present.

2) How can I apply a groove to only a portion of the outer perimeter? Can't seem to do this.

[Tech3]

Please post a a drawing so we can help you.