I'm using Visual Studio 2015. I wanted to drag and drop OleDataAdapter from the data section of WebForm designer and didn't find it, so I Installed the System.Data.OleDb namespace using Nuget (From Console typed Install-Package ...). Now I still don't see it in the data section of WebForm designer, and when I try to add it manually in code (System.Data.OleDb.OleDbDataAdapter) I get an "ambiguous in namespace" error. Is this because I now have two versions of this namespace? I tried to uninstall the namespace in NuGet and still get the error. I also looked at the list of references and only saw the namespace listed once. Most importantly, how can I fix this error? and Secondly, how do I get OleDataAdapter to show up under the data section in WebForm designer?