Problem loading package

Question

I'm a new user and I'm trying to load a package in Mathematica 11.0.

I've copied the DisturbingFunction.m package to %appdata%\Mathematica\Applications but after this I can't load it. I've tried with

<< DisturbingFunction`
Get[DisturbingFunction`]
Needs[DisturbingFunction`]

but none of this results. In the first two I don't get any message, but in the last I get

Needs::nocont: Context DisturbingFunction` was not created when Needs was evaluated.

Can you figure any reason why is this happening? Thank you!

Edit 1

Following Kuba's suggestion, the first time I run $Packages I get

{"GetFEKernelInit`", "StreamingLoader`", \
"SymbolicMachineLearningLoader`", "IconizeLoader`", \
"HTTPHandlingLoader`", "CloudObjectLoader`", "ResourceLocator`", \
"PacletManager`", "System`", "Global`"}

After running Get

{"CURLInfo`", "CURLLink`Cookies`", "OAuthSigning`", "CURLLink`HTTP`", \
"CURLLink`", "QuantityUnits`", "GetFEKernelInit`", \
"StreamingLoader`", "SymbolicMachineLearningLoader`", \
"IconizeLoader`", "HTTPHandlingLoader`", "CloudObjectLoader`", \
"ResourceLocator`", "PacletManager`", "System`", "Global`"}

Answer 1

When you look inside the DisturbinFunction.m file you see the call

BeginPackage["Perturbations`DisturbingFunction`",
  "Perturbations`Common`PerturbationsCommon`"]

This tells you that this file is part of a larger package Pertubations. Additionally, you see that it needs a second package Perturbations`Common`PerturbationsCommon`.

The easiest way is to ask the author for the complete package.