You have already answered yourself why your performance is not good enough. Do not blame on the company for not giving you a raise when you already admitted it yourself your shortcoming when doing the work. A simple job and yet you can make mistakes just because it is too boring. Giving excuses to justify yourself when you have not done your best is not what an employee or an individual should have. Before the start of a job make sure you be very clear of job scope and whether or not it's right for you. Good luck in finding another job if you choose to and please do not waste your time and your boss' for the next job.