Try running the command without doing the sudo, instead become root and try it.

$ sudo su -
$ /sbin/insmod hello1.ko

Try running the command without doing the sudo, instead become root and try it.

$ sudo su -
$ /sbin/insmod hello1.ko

Also take a look in dmesg to see if there are any additional messages as to what went wrong, and also take a peek at the module using modinfo.

$ modinfo /dir/to/mod/hello1.ko