I have the following code to create a database in C#, but the application doesn't release the database file when the connection is closed. What am I doing wrong?

public class FirebirdDatabase
{
FbConnection connection;

public void CreateDatabase()
{
try
{
FbConnectionStringBuilder cs = new FbConnectionStringBuilder();
cs.Database = "C:\TestDb.GDB";
cs.UserID = "SYSDBA";
cs.Password = "masterkey";

FbConnection.CreateDatabase(cs.ToString(), true);
this.connection = new FbConnection(cs.ToString());
this.connection.Open();
this.connection.Close(); //doesn't release DB file
this.connection.Dispose(); //doesn't release DB file
File.Delete(cs.Database); //fails here!
}
catch
{
}
}
}


Full error message:

Code:
The process cannot access the file 'C:\TestDb.GDB' because it is being used by another process


Why is it still locked?

I'm using the latest releases:

- FirebirdSql.Data.FirebirdClient.dll v2.6.0.0
- Firebird Server v2.5.0.26074

I posted this problem on another board but got no response. I am completely stuck! Please help.