How to create Berkeley database using .Net?

I'm using the following code to create a Berkeley DB but I'm receiving an error on the last line:

The type initializer for 'BerkeleyDB.Internal.libdb_csharpPINVOKE' threw an exception.

Code:

Dim DB As DatabaseEnvironment
Dim Config As DatabaseEnvironmentConfig

Config = New DatabaseEnvironmentConfig
Config.Create = True

DB = DatabaseEnvironment.Open("d:\database.db", Config)

Does anyone know what I am doing wrong please ?

I'm using VB Express 2010 with the .Net Framework 4.0

Full Stack :

System.TypeInitializationException: The type initializer for 'BerkeleyDB.Internal.libdb_csharpPINVOKE' threw an exception. ---> 
System.TypeInitializationException: The type initializer for 'SWIGStringHelper' threw an exception. 
System.DllNotFoundException: Unable to load DLL 'libdb_csharp61': Le module spécifié est introuvable. 
(Exception from HRESULT: 0x8007007E) at BerkeleyDB.Internal.libdb_csharpPINVOKE.SWIGStringHelper.SWIGRegisterStringCallback_libdb_csharp(SWIGStringDelegate stringDelegate)
at BerkeleyDB.Internal.libdb_csharpPINVOKE.SWIGStringHelper..cctor() 
in C:\carol\db-6.1.23\lang\csharp\src\Internal\libdb_csharpPINVOKE.cs:line 29     
--- End of inner exception stack trace ---     
at BerkeleyDB.Internal.libdb_csharpPINVOKE.SWIGStringHelper..ctor()     
at BerkeleyDB.Internal.libdb_csharpPINVOKE..cctor() 
in C:\carol\db-6.1.23\lang\csharp\src\Internal\libdb_csharpPINVOKE.cs:line 33     
--- End of inner exception stack trace ---     
at BerkeleyDB.Internal.libdb_csharpPINVOKE.new_DB_ENV(UInt32 jarg1)     
at BerkeleyDB.Internal.DB_ENV..ctor(UInt32 flags) 
in C:\carol\db-6.1.23\lang\csharp\src\Internal\DB_ENV.cs:line 276     
at BerkeleyDB.DatabaseEnvironment..ctor(UInt32 flags) 
in C:\carol\db-6.1.23\lang\csharp\src\DatabaseEnvironment.cs:line 174     
at BerkeleyDB.DatabaseEnvironment.Open(String home, DatabaseEnvironmentConfig cfg) 
in C:\carol\db-6.1.23\lang\csharp\src\DatabaseEnvironment.cs:line 2705     
at WindowsApplication1.Form1.Form1_Load(Object sender, EventArgs e) 
in C:\Documents and Settings\Steven\Local Settings\Application Data\Temporary Projects\WindowsApplication1\Form1.vb:line 13"

1. Make sure your .net project is set to .NET 4.0
2. Build as x86
3. libdb_csharp61.dll is in your /bin/debug folder