/scon doesn't produce the correct error messages when specifing and invalid 'con'.
Try this: /scon 32000 echo -s Test
6.16's error: * No such connection id: 31998
6.17's error: * No such connection id: 31999
From mIRC help:
The /scon command works in exactly the same way, except that N represents the Nth connection, not a connection id value.
Error should read more like: * No such connection: 32000
Correct number specified in error and since that number is NOT a connection id, remove "id".