Can't convert from Server Core to GUI

Hi guys. I'm practicing cmdlets, and I was successfully able to convert from the GUI to server core, but I can't reverse the process.
Install-WindowsFeature Server-Gui-Mgmt-Infra,Server-Gui-Shell -Restart brings up an error saying "Install-WindowsFeature is not recognized..."
Anybody know how to fix this?
Install-WindowsFeature Server-Gui-Mgmt-Infra,Server-Gui-Shell -Restart brings up an error saying "Install-WindowsFeature is not recognized..."
Anybody know how to fix this?
Comments
the reason why I ask, if it's not 2012, then you have to use and not Install-WindowsFeature
Like Dyasis says there's like two versions of the command, and the older one is Add-WindowsFeature
Also if the module is not imported that could be the problem, let us know what ends up fixing it for you
Here's some more info on that cmdlet
Install-WindowsFeature