I don't particularly wish to be rude, new chess problems are to be welcomed (at all levels of difficulty), but you really need to check this one more thoroughly.
It certainly is mate in five, but there are at least a dozen possible first moves (and for your tree to take into all possible branches, there are hundreds of possible combinations).
Originally posted by c0lefalkA computer-test of the problem shows 12 different solutions:
[fen]4r1k1/3p4/BR1Np1np/5NpP/p7/PQ5P/1B2PP2/2R3K1 w - - 0 1[/fen]
Mate in 5. PM me with the solution.
http://www.chessproblems.com/prob.php?id=3172
There is also a helpmate in 2, if you want.
1.Nd6*e8 !
1.Rb6-b8 !
1.h5*g6 !
1.Nf5*h6 + !
1.Nf5-e7 + !
1.Qb3-c2 !
1.Qb3-d5 !
1.Qb3*a4 !
1.Qb3-b5 !
1.Qb3-e3 !
1.Qb3-d3 !
1.Qb3-c3 !