You did pretty well, but @Transistor is correct that the horizontal line needs to be extended. Maybe it looks like this. However, I don't think the inclined plane is correct as there will be another line (shown in red) to connect the corners.
It's a tricky one.
Figure 1. Your isometric is missing this line.
Figure 2. A clue. The six-cornered shape is flat so it must be a plane going through these three points. Can you draw it?
Figure 3. The correct isometric view.
Figure 4. Slide 25 by Shelly Wilke on SlideShare. This and slide 9 may be instructive.
I see 4-solutions. I added straight lines (in GIMP) to represent canted faces. Either the original posted by NMech along with either or both surfaces as canted are also viable alternatives.
(As NMech noted, they could have curvature (except you might then have to show the center of the arc, unless they were b-splines(?).)