brute force with 11 length password(MD4)

[Athlon64]

Hello,
I was trying to recover a 11 length password  with brute force, MD4
I don't understant why  this did not work...

hashcat64.exe -m 900 -a 3 -w 3 -O hashmd4.txt ?h?h?h?h?h?h?h?h?h?h?h --increment --increment-min 11 --increment-max 11

hashcat (v5.1.0) starting...

* Device #1: WARNING! Kernel exec timeout is not disabled.
            This may cause "CL_OUT_OF_RESOURCES" or related errors.
            To disable the timeout, see: https://hashcat.net/q/timeoutpatch
OpenCL Platform #1: NVIDIA Corporation
======================================
* Device #1: GeForce GTX 1060 3GB, 768/3072 MB allocatable, 9MCU

OpenCL Platform #2: Intel(R) Corporation
========================================
* Device #2: AMD Ryzen 7 1700 Eight-Core Processor, skipped.

Hashes: 1 digests; 1 unique digests, 1 unique salts
Bitmaps: 16 bits, 65536 entries, 0x0000ffff mask, 262144 bytes, 5/13 rotates

Applicable optimizers:
* Optimized-Kernel
* Zero-Byte
* Precompute-Init
* Precompute-Merkle-Demgard
* Meet-In-The-Middle
* Early-Skip
* Not-Salted
* Not-Iterated
* Single-Hash
* Single-Salt
* Brute-Force
* Raw-Hash

Minimum password length supported by kernel: 0
Maximum password length supported by kernel: 55

Watchdog: Temperature abort trigger set to 90c

Approaching final keyspace - workload adjusted.

Session..........: hashcat
Status...........: Exhausted
Hash.Type........: MD4
Hash.Target......: 9991a482c1ad810b731bcfbeae00bf5b
Time.Started.....: Fri Nov 22 02:02:19 2019 (18 mins, 12 secs)
Time.Estimated...: Fri Nov 22 02:20:31 2019 (0 secs)
Guess.Mask.......: ?h?h?h?h?h?h?h?h?h?h?h [11]
Guess.Queue......: 1/1 (100.00%)
Speed.#1.........: 16200.1 MH/s (66.07ms) @ Accel:256 Loops:512 Thr:1024 Vec:1
Recovered........: 0/1 (0.00%) Digests, 0/1 (0.00%) Salts
Progress.........: 17592186044416/17592186044416 (100.00%)
Rejected.........: 0/17592186044416 (0.00%)
Restore.Point....: 4294967296/4294967296 (100.00%)
Restore.Sub.#1...: Salt:0 Amplifier:3584-4096 Iteration:0-512
Candidates.#1....: 12fe1999f6e -> 6e6f5f6ef6e
Hardware.Mon.#1..: Temp: 67c Fan: 47% Util: 92% Core:1898MHz Mem:3802MHz Bus:16

Started: Fri Nov 22 02:02:15 2019
Stopped: Fri Nov 22 02:20:33 2019

=============

could someone explain please ?