sqlite3_step(statement) == SQLITE_DONE returning false all the time

Guys I have an issue with my snippet. I must also say I'm a newbie. I'm trying to insert data in to sqlite. but I keeps failing as sqlite_step == sqlite_done returns false all the time. Am I doing something wrong here. I had done something similar before and it was working fine. following is the code

sqlite3_stmt *statement;
const char *dbpath = [_databasePath UTF8String];

if(sqlite3_open(dbpath, &_db) == SQLITE_OK){
    NSString *insertSQL = [NSString stringWithFormat:@"INSERT INTO userInfo (name, email, username, password) VALUES (\"%@\",\"%@\",\"%@\",\"%@\")", self.txtName.text, self.txtEmail.text, self.txtUsername.text, self.txtPassword.text];
    if([self validateRegistration])
    {
        const char *insert_statement = [insertSQL UTF8String];
        sqlite3_prepare_v2(_db, insert_statement, -1, &statement, NULL);

        if(sqlite3_step(statement) == SQLITE_DONE){
            [self showUIAlertWithMessage:@"User added to the database" andTitle:@"Message"];
            self.txtName.text = @"";
            self.txtEmail.text = @"";
            self.txtUsername.text = @"";
            self.txtPassword.text = @"";
            self.txtConfirmPassword.text = @"";
        }else{
            [self showUIAlertWithMessage:@"Failed to add the user" andTitle:@"Error"];
        }
        sqlite3_finalize(statement);
        sqlite3_close(_db);
    }
}

I had this issue because I haven't updated my create table statement according to my insert statements as I had made some changed some values that I am inserting.