I have a problem when using an INSERT statement, ASP.NET?

I'm using C# and Access database. I've written the INSERT statement several times, but this time it is not working. I don't know why

Here's some of the code:

con.Open();

OleDbCommand cmd = new OleDbCommand();

cmd.Connection = con;

cmd.CommandType = CommandType.Text;

cmd.CommandText = string.Format("INSERT INTO Customers (Username, Password, fName, lName, Account, PhoneNumber, Email) VALUES ('{0}','{1}','{2}','{3}','{4}','{5}','{6}')", usertbx.Text, Passwordtbx.Text, fntbx.Text, lntbx.Text, accounttbx.Text, phtbx.Text, emailtbx.Text);

int rows = cmd.ExecuteNonQuery();