If you are a Windows Insider and received the latest Build 14331/14332 than you may have some troubles getting choco command running in a Powershell. If you try install a package – it doesn’t matter which – than you will get followin output:
(example of installing netscan)
What happend… a bug in Powershell. So, if you like to avoid this, than you have some options 
1) Go back to a stable previous Build
2) Wait, until everything gets fixed
3) do the following:
Open file “C:\ProgramData\Chocolatey\helpers\chocolateyScriptRunner.ps1”. Replace
[alias(“params”)][alias(“parameters”)][alias(“pkgParams”)] in the header of that file by
[alias(“params”,”parameters”,”pkgParams”)]
as a quick fix. After that, you can try your install once again. It should now succeed.
Please see this post, where I got this fix from, for details: https://github.com/chocolatey/choco/issues/659
0.9.9.12 was released as well to combat this issue (and only this issue).