このコードを試すと、次のエラーが発生します。
TaxiEntities db = new TaxiEntities();
bool IsUserPassCorrected = db.tblOperators.Any(item => item.UserName.ToLower() == txtUserName.Text.ToLower() &&
item.Password == Convert.ToInt32(txtPassWord.Text));
if (!IsUserPassCorrected)
{
MessageBox.Show("Username or Password is incorrected! Please try again");
}