Your command does not do its job because you did not start it as administrator.
Happens to me all the time, then I need to run powershell from a non powershell...
To start a powershell with admin rights (so you are an administrator but did not start the shell as it) you use the following command from the current powershell:
Start-Process powershell -verb runas
About the Author
Wim Peeters is electronics engineer with an additional master in IT and over 30 years of experience including time spent in support, development, consulting, training and database administration. Wim has worked with SQL Server since version 6.5. He has developed in C/C++, Java and C# on Windows and Linux in different European countries and different European languages. He writes knowledge base articles to solve IT problems and publishes them on the Lubby Knowledge Platform where he is one of the most important contributors and the main developer.