Select the “Start” button, then type “CMD“.
Right-click “Command Prompt” and select “Run as Administrator“.
Type the following, then press “Enter“:
regsvr32 schmmgmt.dll
You should receive a message that registration succeeded.
Now you should be able to add the snap-in using these steps:
Hold the Windows Key and press “R” to bring up the Run box.
Type “mmc“, then press “Enter“. The Microsoft Management Console opens.
Select “File” > “Add/Remove Snap-In“.
Select “Active Directory Schema“, then select “Add“.
Select “OK“.
