Firebird DB connection using C#

Hello everybody!

So, I need to connect to Firebird SQL database from Unity. I’ve installed:
.NET 4.5;
Firebird 2.5.2;
Firebird ADO.NET Data Provider 4.1.0.0 for .NET 4.5

and wrote following script:

using UnityEngine;
using System.Collections;
using System.Data;
using FirebirdSql.Data.FirebirdClient;

public class SQLConnection : MonoBehaviour {

// Use this for initialization
void Start () {
	string conn = "Database=D:\\DB\\MAIN.FDB;" + "User=SYSDBA;" + "Password=masterkey;" + "Dialect=3;" + "Server=localhost";
	FbConnection dbcon = new FbConnection(conn);
}

// Update is called once per frame
void Update () {

}

}

When executing it, I get this error:
TypeLoadException: Could not load type ‘FirebirdSql.Data.FirebirdClient.FbConnectionString’ from assembly ‘FirebirdSql.Data.FirebirdClient, Version=4.1.0.0, Culture=neutral, PublicKeyToken=3750abcc3150b00c’.
(wrapper remoting-invoke-with-check) FirebirdSql.Data.FirebirdClient.FbConnection:.ctor (string)
SQLConnection.Start () (at Assets/SQLConnection.cs:12)

I wrote that script according to Firebird .NET provider documentation, so I don’t have any ideas about that error. Help please!

Maybe it will be helpful - I downloaded Firebird ADO.NET Data Provider 2.5.2 for .NET 3.5/2.0 and it’s dll works correctly.