In you're previously posted picture, you have...
1. the left side constrained vertical,
2. the left and right sides constrained parallel to each other (meaning the right side must also be vertical)
Therefor, geometrically speaking, the distance between the left side and the right side must be the same at the top of them, at the bottom of them, or indeed anywhere along their length. So you've got a situation wherein you can't close the bottom and the top with different length lines. It's just a geometric impossibility.
Hopefully by watching my video you've learned how to correct that situation. Delete those parallel constraints between the left and right sides, because the right side is going to have to lean over. Make the two unconnected endpoints at the top/right coincident with each other. The top line is already constrained perpendicular to the left line, so either constrain the bottom line perpendicular to it also, constrain the bottom line horizontal, or constrain the top and bottom lines parallel with each other.