how to open SQLite connection in wcf

I have some WCF Code that accesses SQLite database, but when i want to open SQLite Connection an error occurred

error message: Fault Exception was Unhandled

error picture: Click to open error message picture

WCF Interface code:

    [ServiceContract]
    public interface IService1
    {
        [OperationContract]
        string openConnection(string query);
    }

WCF Interface Implementation code:

public class Service1 : IService1
    {
        public string openConnection(string query)
        {
            SQLiteConnection connection = new SQLiteConnection();
            connection.ConnectionString = @"Data Source=C:\SqliteDBFile.sqlite;Version=3;";
            try
            {
                connection.Open();
            }
            catch(FaultException f)
            {
                throw new FaultException("Error occurred");
            }

            return "OK";
        }
    }

Client Code:

private void button1_Click(object sender, EventArgs e)
{
    ServiceReference1.Service1Client client = new ServiceRefrence1.Service1Client();
    MessageBox.Show(client.openConnection("select * from users"));
}  

Error occurred when client sent request to wcf service to open sqlite connection.

Where is my Wrong?

Please Help me!