NuGet - install.ps1 does not get called

I'm trying to create my first NuGet package. I don't know why my install.ps1 script does not get called. This is directory structure

--Package| - MyPackage.nuspec - tools |  - Install.ps1  - some_xml_file

I build package using this command linenuget.exe pack MyPackage.nuspec

When I Install-Package from VS Package Manager Console install.ps1 does not get called.

I thought that maybe I had some errors in script and that's the reason so I commented out everything but

param($installPath, $toolsPath, $package, $project)"ECHO"

But I don't see ECHO appearing in Package Manager Console. What can be wrong?