There seem to be multiple valid solutions to a puzzle in the final car that are not accepted

[captainnibbles]

We got stuck for a bit with the numbered block puzzle in the engine car. My partner came up with a solution that, when drawn on paper, meets all the criteria of the only "correct" solution: every end point is connected in a single graph, there are no "open" connections, to either unincluded letters or the middle area, there is no need to fill every space, and there are no internal loops. We couldnt think of any reason why his solution was any different than the "correct" one.

The needed connections for this puzzle are B, K, I, G, F, E and his solution is
5 | 4 |
11 | 7| 2
1| 3| 6

Any reason this shouldnt work? If there are multiple solutions that follow the rules, they ought to be accepted.