Cuda-samples error when building with Nvidia-Docker?

I’m using Ubuntu 20 and CUDA 11.1

I followed the steps in here:

When I got to sudo nvidia-docker build -t device-query ., it says

unable to locate package cuda-samples
the command '/bin/sh -c apt-get update && apt-get install -y --no-install-recommends
cuda-samples:-$CUDA_PKG_VERSION && -rm -rf /var/lib/apt/lists/*'
returned a non-zero code: 100

The Dockerfile is:

# FROM defines the base image
FROM nvidia/cuda

# RUN executes a shell command
# You can chain multiple commands together with && 
# A \ is used to split long lines to help with readability
# This particular instruction installs the source files 
# for deviceQuery by installing the CUDA samples via apt
RUN apt-get update && apt-get install -y --no-install-recommends \
        cuda-samples-$CUDA_PKG_VERSION && \
    rm -rf /var/lib/apt/lists/*

# set the working directory 
WORKDIR /usr/local/cuda-11.1/samples/1_Utilities/deviceQuery

RUN make

# CMD defines the default command to be run in the container 
# CMD is overridden by supplying a command + arguments to 
# `docker run`, e.g. `nvcc --version` or `bash`
CMD ./deviceQuery

can anyone help?