What you call properly ?
Hoe was fixed long ago because raising and entire wall from the top of another was a bug

Originally posted by LogosGreyknight:

Since I've been playing again, the hoe doesn't seem to properly level out the ground, anyone else with this issue?

Along what the others have said about using a pick, you can also press SHIFT while using the hoe.

The hoe by itself won't fully level the ground. You need to fill and use a pick to knock down some as you go.

The hoe has a limit to how much it can raise/lower. If there are still holes left you need to fill them in with "rais ground" and bumps need to be taken down with a pick.