I created a method called "AddCustomer" using a direct SQL command with Access database. But it doesn't execute. What did I do wrong?

Thanks in advance,
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public string AddCustomer(string lastname,
            string firstname,
            string email,
            string upassword,
            string address,
            string prefix,
            string phonenumber)
        {
            // Create Instance of Connection and Command Object
            String strConn ="Provider=Microsoft.Jet.OleDb.4.0;";
            strConn += @"Data Source=C:\MyProject\DB\HowardGroupWeb.mdb";
            OleDbConnection myConnection = new OleDbConnection(strConn) ;

            string strSQL = "INSERT INTO Users (FirstName, LastName, Email, UserPwd, Address, Prefix, PhoneNumber, VerifiedDate) "+
                "VALUE ('"+firstname+"','"+lastname+"','"+email+"','"+upa ssword+"','"+address+"','"+prefix+"','"+phonenumbe r+"','"+DateTime.Today.ToString()+"')";

            OleDbCommand myCommand = new OleDbCommand(strSQL,myConnection);

            UserDetails myUserDetails = new UserDetails();
            OleDbDataReader myDataReader = null;
            string searchSQL="SELECT UserID FROM Users WHERE FisrtName=firstname AND LastName=lastname AND UserPwd=upassword"+
                "Email=email AND PhoneNumber=phonenumber;";


            try
            {
                myConnection.Open();
                myCommand.ExecuteNonQuery();
                myConnection.Close();

                OleDbCommand searchCommand = new OleDbCommand(searchSQL,myConnection);
                myConnection.Open();
                myDataReader = searchCommand.ExecuteReader();
                if(myDataReader.Read()==true)
                {
                    myUserDetails.UserID = Convert.ToInt32(myDataReader["UserID"].ToString());
                }
                myDataReader.Close();
                myConnection.Close();

                return myUserDetails.UserID.ToString();
            }
            catch(OleDbException Oexc)
            {
                return Oexc.ToString();
            }
        }

I found the bugs. Thanks!