C4W2 ungraded assignment Can't build docker image property

When I run $ docker build -t mlepc4w2-ugl:no-batch as the instructions showed, I got the following message and ends up with no proper docker image has been built, so I can’t proceed to the next step. Docker is very new to me, did I run things in the wrong way? Thanks!

“docker build” requires exactly 1 argument.
See ‘docker build --help’.

Usage: docker build [OPTIONS] PATH | URL | -

Build an image from a Dockerfile

you are mising the trailing dot. It indicates to look for Dockerfile at the current directory

docker build -t mlepc4w2-ugl:no-batch .

Thank you very much!!