Nethack Sokoban level 4B is not solvable. Here's what it should look like: http://nethackwiki.com/wiki/Sokoban_Level_4b
You used an old unsolvable map from when Sokoban was first introduced in 3.3.0, and was fixed in 3.3.1.
The one you "Updated" is solvable as listed here: http://nethackwiki.com/wiki/Sokoban_Level_3a