COMMAND: /usr/local/nagios/libexec/check_nt -H xxx.xxx.xxx -s "xxxxx" -p 12489 -l MSSQL\$MICROSOFT
OUTPUT : Failed to open service MSSQL$MICROSOFT: 1060: Le service spécifié n'existe pas en tant que service installé.
I tried with
MSSQL$$MICROSOFT##SSEE --> not ok
]MSSQL\$MICROSOFT##SSEE --> not ok
Are you using the test command on the GUI? If so, I wouldn't recommend that. It has issues with special characters. Can you make this work from the command line?