Assembly Not Found In SQL Catalog For VSS

I'm trying to connect to VSS from my CLR procedure.
I'm getting this error..
Assembly
'microsoft.visualstudio.sourcesafe.interop, version=5.2.0.0,
culture=neutral, publickeytoken=b03f5f7f11d50a3a.' was not found in the
SQL catalog.

I added reference to VSS dll by opening the project file in notepad, as I couldn't right-click and do an add reference.

Here's the code...


using System;
using System.Data;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using Microsoft.SqlServer.Server;
using Microsoft.VisualStudio.SourceSafe.Interop;


public partial class StoredProcedures
{
[Microsoft.SqlServer.Server.SqlProcedure]
public static void PrintToday()
{
try
{
//'�� The SourceSafe INI file.
string iniVssPath = "C:/CLRVSS";

//'�� The SourceSafe User ID/Password.
string cVSSUserName = "Admin";
string cVSSPassword = "";


VSSDatabaseClass vssLib = null;
vssLib = new VSSDatabaseClass();
vssLib.Open(iniVssPath, cVSSUserName, cVSSPassword);

VSSItem VSS_Item = vssLib.get_VSSItem("$/Test", false);
VSS_Item.Destroy();

SqlPipe p;
p = SqlContext.Pipe;
p.Send("success");
}
catch
{
SqlPipe p;
p = SqlContext.Pipe;
p.Send("error");
}
}
};