Freebsd shell script not starting. Why?

Question

linux

It does not start if I simply write in the console check.sh. If sh check.shit works.
Script rights:

-rwxr-xr-x  1 root      wheel   524B Jan 19 14:04 check.sh

This is how the script starts

#!/bin/sh
echo "script start" >> "/mylog"
...

/bin/sh is in the system and works
Everything is done under root

Answer 1

./check.sh