I need to use Server class which is stored in Microsoft.SqlServer.Smo.dll I don\'t see this assembly in usual References dialog. I have found it at C:/Program Files/Microsof
I know this is an old question, but I just ran into the same issue. @Mitch_Wheat is correct that as a minimum you need references to the 4 SMO assemblies. Trying to add all 4 at once, however, gave me the error you listed.
Adding the assemblies one at a time bypassed the error.